required field validator not working

Question

 I am trying to validate to inittial value in dropdwinlist using required filed validator but it is not working. please help any one

 

 

<table id="tbl_AddmsnDetail" class="inner_tbl">

<tr>

<td class="td1">

<p><span style="color: red;">*</span> Select Course :<br />

&nbsp (????? ????? ?????? ??????)</p>

</td>

<td class="td1">

<asp:DropDownList ID="drpdwn_SelectCourse" AppendDataBoundItems="true" CausesValidation="true" AutoPostBack="true" CssClass="inner-dropdown" runat="server" DataSourceID="SqlDataSource5" DataTextField="CourseName" DataValueField="CourseID" OnSelectedIndexChanged="drpdwn_SelectCourse_SelectedIndexChanged">

<asp:ListItem> --- Pick One --- </asp:ListItem>

</asp:DropDownList>

<asp:SqlDataSource ID="SqlDataSource5" runat="server" ConnectionString="<%$ ConnectionStrings:iDiary_RBSCollegeConnectionString1 %>" SelectCommand="SELECT [CourseName],[CourseID] FROM [CourseMaster] WHERE ([Admission_Open_Trigger] = @Admission_Open_Trigger) ORDER BY [CourseID]">

<SelectParameters>

<asp:Parameter DefaultValue="1" Name="Admission_Open_Trigger" Type="Int32" />

</SelectParameters>

</asp:SqlDataSource>

<br />

<asp:RequiredFieldValidator Font-Size="9px" ForeColor="Red" ID="RequiredFieldValidator1" runat="server"

ErrorMessage="Please select" ControlToValidate="drpdwn_SelectCourse"

InitialValue="--- Pick One ---"></asp:RequiredFieldValidator>

<asp:Label ID="lbl_courseid" runat="server" Visible="false" Text="Label"></asp:Label>

<asp:Label ID="lbl_coursetype" runat="server" Visible="false" Text="Label"></asp:Label>

</td>

<td class="td1">

<p><span style="color: red;">*</span> Select Group :<br />

&nbsp (????? ?? ??? ???)</p>

</td>

<td class="td1">

<asp:DropDownList ID="drpdwn_group" AutoPostBack="true" DataTextField="GrpName" CssClass="inner-dropdown" OnSelectedIndexChanged="drpdwn_group_SelectedIndexChanged" runat="server">

</asp:DropDownList>

</td>

</tr>

</table>

<table id="subject_typ1" runat="server" visible="false">

<tr>

<td class="td1">

<p><span style="color: red;">*</span> Select Subject1 :<br />

&nbsp (????)</p>

</td>

<td class="td1">

<asp:DropDownList ID="drpdwn_SelectSubject1" CssClass="inner-dropdown" runat="server" DataTextField="SubjectName" DataValueField="SubjectName">

<asp:ListItem> --- Pick One --- </asp:ListItem>

</asp:DropDownList>

<br />

<asp:RequiredFieldValidator CssClass="validator" ID="RequiredFieldValidator10" runat="server"

ErrorMessage="Please select" ControlToValidate="drpdwn_SelectSubject1"

InitialValue="--- Pick One ---"></asp:RequiredFieldValidator>

</td>

<td class="td1">

<p><span style="color: red;">*</span> Select Subject2 :<br />

&nbsp (????)</p>

</td>

<td class="td1">

<asp:DropDownList ID="drpdwn_SelectSubject2" CssClass="inner-dropdown" runat="server" DataTextField="SubjectName" DataValueField="SubjectName">

<asp:ListItem> --- Pick One --- </asp:ListItem>

</asp:DropDownList>

<br />

<asp:RequiredFieldValidator CssClass="validator" ID="RequiredFieldValidator11" runat="server"

ErrorMessage="Please select" ControlToValidate="drpdwn_SelectSubject2"

InitialValue="--- Pick One ---"></asp:RequiredFieldValidator>

</td>

</tr>

<tr>

<td class="td1">

<p><span style="color: red;">*</span> Select Subject3 :<br />

&nbsp (????)</p>

</td>

<td class="td1">

<asp:DropDownList ID="drpdwn_SelectSubject3" CssClass="inner-dropdown" runat="server" DataTextField="SubjectName" DataValueField="SubjectName">

<asp:ListItem> --- Pick One --- </asp:ListItem>

</asp:DropDownList>

<br />

<asp:RequiredFieldValidator CssClass="validator" ID="RequiredFieldValidator12" runat="server"

ErrorMessage="Please select" ControlToValidate="drpdwn_SelectSubject3"

InitialValue="--- Pick One ---"></asp:RequiredFieldValidator></td>

<td class="td1">

<p><span style="color: red;">*</span> Select Subject4 :<br />

&nbsp (????)</p>

</td>

<td class="td1">

<asp:DropDownList ID="drpdwn_SelectSubject4" CssClass="inner-dropdown" runat="server" DataTextField="SubjectName" DataValueField="SubjectName">

<asp:ListItem> --- Pick One --- </asp:ListItem>

</asp:DropDownList>

<br />

<asp:RequiredFieldValidator CssClass="validator" ID="RequiredFieldValidator13" runat="server"

ErrorMessage="Please select" ControlToValidate="drpdwn_SelectSubject4"

InitialValue="--- Pick One ---"></asp:RequiredFieldValidator></td>

</tr>

<tr>

<td class="td1">

<p><span style="color: red;">*</span> Select Subject5 :<br />

&nbsp (????)</p>

</td>

<td class="td1">

<asp:DropDownList ID="drpdwn_SelectSubject5" CssClass="inner-dropdown" runat="server" DataTextField="SubjectName" DataValueField="SubjectName">

<asp:ListItem> --- Pick One --- </asp:ListItem>

</asp:DropDownList>

<br />

<asp:RequiredFieldValidator CssClass="validator" ID="RequiredFieldValidator14" runat="server"

ErrorMessage="Please select" ControlToValidate="drpdwn_SelectSubject5"

InitialValue="--- Pick One ---"></asp:RequiredFieldValidator></td>

<td class="td1">

<p><span style="color: red;">*</span> Select Subject6 :<br />

&nbsp (????)</p>

</td>

<td class="td1">

<asp:DropDownList ID="drpdwn_SelectSubject6" CssClass="inner-dropdown" runat="server" DataTextField="SubjectName" DataValueField="SubjectName">

<asp:ListItem> --- Pick One --- </asp:ListItem>

</asp:DropDownList>

<br />

<asp:RequiredFieldValidator CssClass="validator" ID="RequiredFieldValidator15" runat="server"

ErrorMessage="Please select" ControlToValidate="drpdwn_SelectSubject6"

InitialValue="--- Pick One ---"></asp:RequiredFieldValidator></td>

</tr>

<tr>

<td class="td1">

<p><span style="color: red;">*</span> Select Subject7 :<br />

&nbsp (????)</p>

</td>

<td class="td1">

<asp:DropDownList ID="drpdwn_SelectSubject7" CssClass="inner-dropdown" runat="server" DataTextField="SubjectName" DataValueField="SubjectName">

<asp:ListItem> --- Pick One --- </asp:ListItem>

</asp:DropDownList>

<br />

<asp:RequiredFieldValidator CssClass="validator" ID="RequiredFieldValidator16" runat="server"

ErrorMessage="Please select" ControlToValidate="drpdwn_SelectSubject7"

InitialValue="--- Pick One ---"></asp:RequiredFieldValidator></td>

<td class="td1">

<p><span style="color: red;">*</span> Select Subject8 :<br />

&nbsp (????)</p>

</td>

<td class="td1">

<asp:DropDownList ID="drpdwn_SelectSubject8" CssClass="inner-dropdown" runat="server" DataTextField="SubjectName" DataValueField="SubjectName">

<asp:ListItem> --- Pick One --- </asp:ListItem>

</asp:DropDownList>

<br />

</td>

</tr>

</table>

<table id="subject_type2" runat="server">

<tr>

<td>

<asp:DataList ID="DataList2" Visible="false" runat="server" DataSourceID="SqlDataSource1">

<ItemTemplate>

<asp:Label Text='<%# Container.ItemIndex + 1 %>' runat="server" ID="Label12" />-

<asp:Label Text='<%# Eval("SubjectName") %>' runat="server" ID="SubjectNameLabel" /><br />

<br />

</ItemTemplate>

</asp:DataList>

<asp:SqlDataSource runat="server" ID="SqlDataSource1" ConnectionString='<%$ ConnectionStrings:iDiary_RBSCollegeConnectionString1 %>' SelectCommand="SELECT [SubjectName] FROM [SubjectsMaster] WHERE ([CourseID] = @CourseID)">

<SelectParameters>

<asp:SessionParameter SessionField="courseid" Name="CourseID" Type="Int32"></asp:SessionParameter>

</SelectParameters>

</asp:SqlDataSource>

</td>

</tr>

</table>

<%--<tr id="MSc_Ag">

<td class="td1">

<p> Enter Subject for M.Sc.(Ag) :</p>

</td>

<td class="td1">

<p>1.)</p><asp:TextBox ID="TextBox2" CssClass="inner-textbox" runat="server"></asp:TextBox>

</td>

<td class="td1">

<p>2.)</p><asp:TextBox ID="TextBox7" CssClass="inner-textbox" runat="server"></asp:TextBox>

</td>

<td class="td1">

<p>3.)</p><asp:TextBox ID="TextBox8" CssClass="inner-textbox" runat="server"></asp:TextBox>

</td>

</tr>--%>

<table>

<tr>

<td class="td1" colspan="4" style="text-align: right">

<asp:Button ID="next2" runat="server" CssClass="btn" CausesValidation="true" Text="Save & Next" OnClick="next2_Click" />

</td>

</tr>

</table>