Hi,
I have a gridview which display the list of student details from the database. I have used webservice in this. what is the problem here is, when i add this web service to the application the data of student is not fetched from the database , but it worked wel when i tried before adding the webservice. I dono what is the problem, Please help me to find out. 
 
DAL:
 public class StudentDALClass
    {
        string constring = System.Configuration.ConfigurationManager.ConnectionStrings["conStr"].ConnectionString;
        /// <summary>
        /// Binding the Gridview
        /// </summary>
        /// <returns></returns>
        public DataTable StudentGridBindDAL()
        {
            SqlConnection con = new SqlConnection(constring); ;
            DataTable dt = new DataTable();
            SqlDataAdapter dataAdapter;
            SqlCommandBuilder commandBuilder;
            try
            {
                con.Open();
                dataAdapter = new SqlDataAdapter("spSelectStudentTable", con);
                commandBuilder = new SqlCommandBuilder(dataAdapter);
                dataAdapter.Fill(dt);
                return dt;
            }
            catch (SqlException)
            {
                throw new Exception("Error Occurred in DB, Please try again later");
               
            }
            catch (NullReferenceException)
            {
                throw new Exception("Invalid data has been passed");
            }
            catch (FormatException)
            {
                throw new Exception("Iput string was not in a correct formate");
            }
            catch (IndexOutOfRangeException)
            {
                throw new Exception("Invaid input has been passed");
            }
            catch (Exception ex)
            {
                throw ex;
            }
            finally
            {
                if (con.State == ConnectionState.Open)
                {
                    con.Close();
                }
            }
        }
} 
BLL:
 public class StudentBLLClass
    {
        StudentDALClass dal = new StudentDALClass();
        /// <summary>
        /// binding the student data to the grid view
        /// </summary>
        /// <returns></returns>
        public DataTable StudnetBindBLL()
        {
            DataTable dt;
            try
            {
                dt = dal.StudentGridBindDAL();
                return dt;
            }
            catch (Exception ex)
            {
                throw ex;
            }
        }
} 
 WEB Service :
  [ServiceContract]
    public interface IService1
    {
        [OperationContract]
        DataTable StudnetBindService();
        [OperationContract]
        void AddStudentService(StudentEntityClass se);
        [OperationContract]
        void UpdateStudentService(StudentEntityClass se);
        [OperationContract]
        void DaleteStudentService(StudentEntityClass se);
    }
 
//implementing interface 
    public class Service1 : IService1
    {
        StudentBLLClass bll = new StudentBLLClass();
        public DataTable StudnetBindService()
        {
            DataTable dt;
            dt = bll.StudnetBindBLL();
            return dt;
        }
        public void AddStudentService(StudentEntityClass se)
        {
            bll.AddStudentBLL(se);
        }
        public void UpdateStudentService(StudentEntityClass se)
        {
            bll.UpdateStudentBLL(se);
        }
        public void DaleteStudentService(StudentEntityClass se)
        {
            bll.DaleteStudentBLL(se);
        }
    }
 Code Behind: StudentBLLClass bll = new StudentBLLClass();
        StudentListServiceReference.Service1Client servicereference = new StudentListServiceReference.Service1Client();
        /// <summary>
        /// Displaying gridview in pageload
        /// </summary>
        /// <param name="sender"></param>
        /// <param name="e"></param>
        protected void Page_Load(object sender, EventArgs e)
        {
            if(!IsPostBack)
            {
                try
                {
                    GridBind();
                }
                catch (Exception ex)
                {
                    Response.Write(ex.Message);
                }
            }
           
        }
EntityLayer:
  public class StudentEntityClass
    {
        public int StudentId { get; set; }
        public string StudentName { get; set; }
        public string EmailId { get; set; }
        public string PhoneNumber { get; set; }
        public string City { get; set; }
} 
 
UI Layer:
<html xmlns="http://www.w3.org/1999/xhtml">
<head runat="server">
    <title></title>
   
</head>
<body>
    <form id="form1" runat="server">
    <h1>List Of Students</h1>
    <div>
        <asp:GridView ID="grdStudentList" runat="server" AutoGenerateColumns="False" Width="500px" Height="200px" 
            DataKeyNames="StudentID" ShowFooter="true" CellPadding="4" ForeColor="#333333" GridLines="None" 
            HorizontalAlign="Center" OnRowCancelingEdit="grdStudentList_RowCancelingEdit" OnRowEditing="grdStudentList_RowEditing" 
            OnRowUpdating="grdStudentList_RowUpdating" OnRowDeleting="grdStudentList_RowDeleting">
            <AlternatingRowStyle BackColor="White" ForeColor="#284775" />
            <Columns>
                <asp:TemplateField HeaderText="Student ID">
                    <ItemTemplate>
                       <asp:Label ID="lblStudentId" runat="server" Text='<%#Bind("StudentID") %>'>'></asp:Label>
                    </ItemTemplate>
                    <FooterTemplate>
                       <asp:TextBox ID="txtStudentID" runat="server" Width="180px"></asp:TextBox>
                    </FooterTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="Student Name">
                    <ItemTemplate>
                        <asp:Label ID="lblStudentName" runat="server" Text='<%#Bind("StudentName") %>'>'></asp:Label>
                    </ItemTemplate>
                    <EditItemTemplate>
                        <asp:TextBox ID="txtEditStudentName" runat="server" Text='<%#Bind("StudentName") %>'>'></asp:TextBox>
                    </EditItemTemplate>
                    <FooterTemplate>
                        <asp:TextBox ID="txtStudentName" runat="server" Width="180px"></asp:TextBox>
                    </FooterTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="Email Id">
                    <ItemTemplate>
                        <asp:Label ID="lblEmailID" runat="server" Text='<%#Bind("EmailID") %>'>'></asp:Label>
                    </ItemTemplate>
                    <EditItemTemplate>
                        <asp:TextBox ID="txtEditEmailID" runat="server" Text='<%#Bind("EmailID") %>'>'></asp:TextBox>
                    </EditItemTemplate>
                    <FooterTemplate>
                        <asp:TextBox ID="txtEmailID" runat="server" Width="180px"></asp:TextBox>
                    </FooterTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="Mobile Number">
                    <ItemTemplate>
                        <asp:Label ID="lblPhoneNumber" runat="server" Text='<%#Bind("PhoneNumber") %>'>'></asp:Label>
                    </ItemTemplate>
                    <EditItemTemplate>
                        <asp:TextBox ID="txtEditPhoneNo" runat="server" Text='<%#Bind("PhoneNumber") %>'>'></asp:TextBox>
                    </EditItemTemplate>
                    <FooterTemplate>
                        <asp:TextBox ID="txtPhoneNo" runat="server" Width="180px"></asp:TextBox>
                    </FooterTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="City">
                    <ItemTemplate>
                        <asp:Label ID="lblCity" runat="server" Text='<%#Bind("City") %>'>'></asp:Label>
                    </ItemTemplate>
                    <EditItemTemplate>
                        <asp:TextBox ID="txtEditCity" runat="server" Text='<%#Bind("City") %>'>'></asp:TextBox>
                    </EditItemTemplate>
                    <FooterTemplate>
                        <asp:TextBox ID="txtCity" runat="server" Width="180px"></asp:TextBox>
                    </FooterTemplate>
                </asp:TemplateField>
                <asp:TemplateField>
                    <ItemTemplate>
                        <asp:Button ID="btnEdit" runat="server" Text="Edit" Font-Bold="true" CommandName="Edit" Width="150px"/>
                    </ItemTemplate>
                    <EditItemTemplate>
                        <asp:Button ID="btnUpdate" runat="server" Text="Update" Font-Bold="true" CommandName="Update" />
                        <asp:Button ID="btnCancel" runat="server" Text="Cancel" Font-Bold="true" CommandName="Cancel" />
                    </EditItemTemplate>
                    <FooterTemplate>
                        <asp:Button ID="btnAdd" runat="server" Text="Add" Width="150px" Font-Bold="true" CommandName="Add" OnClick="AddButtonClick" />
                    </FooterTemplate>
                </asp:TemplateField>
                <asp:TemplateField>
                    <ItemTemplate>
                        <asp:Button ID="btnDelete" runat="server" Text="Delete" Font-Bold="true" CommandName="Delete" Width="150px" />
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
            <EditRowStyle BackColor="#999999" />
            <FooterStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
            <HeaderStyle BackColor="#5D7B9D" Font-Bold="True" ForeColor="White" />
            <PagerStyle BackColor="#284775" ForeColor="White" HorizontalAlign="Center" />
            <RowStyle BackColor="#F7F6F3" ForeColor="#333333" />
            <SelectedRowStyle BackColor="#E2DED6" Font-Bold="True" ForeColor="#333333" />
            <SortedAscendingCellStyle BackColor="#E9E7E2" />
            <SortedAscendingHeaderStyle BackColor="#506C8C" />
            <SortedDescendingCellStyle BackColor="#FFFDF8" />
            <SortedDescendingHeaderStyle BackColor="#6F8DAE" />
            <RowStyle HorizontalAlign="Center"/>
        </asp:GridView>
    </div>
    </form>
</body>
</html>
WEB CONFIG FILE:
<configuration>
  <connectionStrings>
    <add name="conStr" connectionString="Database=AdventureWorks2008;Server=CHV8LTDBNC01\LENTRACSDB2008;Integrated Security=False;UID=sqltrainer;PWD=Welcome123" providerName="System.Data.SqlClient"/>
  </connectionStrings>
  <appSettings>
    <add key="aspnet:UseTaskFriendlySynchronizationContext" value="true" />
  </appSettings>
  <system.web>
    <compilation debug="true" targetFramework="4.5" />
    <httpRuntime targetFramework="4.5"/>
  </system.web>
  <system.serviceModel>
    <behaviors>
      <serviceBehaviors>
        <behavior>
          <!-- To avoid disclosing metadata information, set the values below to false before deployment -->
          <serviceMetadata httpGetEnabled="true" httpsGetEnabled="true"/>
          <!-- To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information -->
          <serviceDebug includeExceptionDetailInFaults="false"/>
        </behavior>
      </serviceBehaviors>
    </behaviors>
    <protocolMapping>
        <add binding="basicHttpsBinding" scheme="https" />
    </protocolMapping>    
    <serviceHostingEnvironment aspNetCompatibilityEnabled="true" multipleSiteBindingsEnabled="true" />
  </system.serviceModel>
  <system.webServer>
    <modules runAllManagedModulesForAllRequests="true"/>
    <!--
        To browse web app root directory during debugging, set the value below to true.
        Set to false before deployment to avoid disclosing web app folder information.
      -->
    <directoryBrowse enabled="true"/>
  </system.webServer>
</configuration>