how to write the update query in 3tire archetucture by using MS_Access

Question

// this is data access layer code
public bool Update(BOL.bolCompanyDetailsMaster obj)
{
dbConnection conn =new dbConnection();
            string sql = "update [CompanyDetailsMaster] set [BranchName]=@BranchName,[Address]=@Address,[PhoneNo]=@PhoneNo,[EmailId]=@EmailId,[CompanyLogo]=@CompanyLogo where BranchCode=@BranchCode";
           
            OleDbParameter[] oledbParameters = new OleDbParameter[6];
//sqlParameters[0] = new SqlParameter("@Srlno", SqlDbType.Int);
//sqlParameters[0].Value = obj.Srlno;
            oledbParameters[0] = new OleDbParameter("@BranchCode", OleDbType.VarChar);
            oledbParameters[0].Value = obj.Branchcode;
            oledbParameters[1] = new OleDbParameter("@BranchName", OleDbType.VarChar);
            oledbParameters[1].Value = obj.Branchname;
            oledbParameters[2] = new OleDbParameter("@Address", OleDbType.VarChar);
            oledbParameters[2].Value = obj.Address;
            oledbParameters[3] = new OleDbParameter("@PhoneNo", OleDbType.VarChar);
            oledbParameters[3].Value = obj.Phoneno;
            oledbParameters[4] = new OleDbParameter("@EmailId", OleDbType.VarChar);
            oledbParameters[4].Value = obj.Emailid;
            oledbParameters[5] = new OleDbParameter("@CompanyLogo", OleDbType.VarChar);
            oledbParameters[5].Value = obj.Companylogo;
            return conn.executeUpdateQuery(sql, oledbParameters);


}
//this is business layer
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;
namespace PayRoll.BOL
{
class bolCompanyDetailsMaster
{
DAL.dalCompanyDetailsMaster dalObj= new PayRoll.DAL.dalCompanyDetailsMaster();
private Int32 m_Srlno;
private string m_Branchcode;
private string m_Branchname;
private string m_Address;
private string m_Phoneno;
private string m_Emailid;
private string m_Companylogo;
        private string m_StdCode;
        private string m_LandLine;
/// <constructor>
/// Constructor bolCompanyDetailsMaster
/// </constructor>
public bolCompanyDetailsMaster()
{
//Initialize the variable here
}
/// <summary>
/// ColumnName:Srlno
/// Data Type:int
/// Length:0
/// </summary>
public Int32 Srlno
{
get
{
return m_Srlno;
}
set
{
m_Srlno = value;
}
}
/// <summary>
/// ColumnName:Branchcode
/// Data Type:VarChar
/// Length:20
/// </summary>
public string Branchcode
{
get
{
return m_Branchcode;
}
set
            {
                if (value == "")
                {
                    throw new InvalidData("Branch Code cannot be empty", "Payroll", MessageBoxButtons.OK, MessageBoxIcon.Exclamation);
                }
if (value.Length > 20)
{
                    throw new InvalidData("The Branchcode  is more length", "Payroll", MessageBoxButtons.OK, MessageBoxIcon.Warning);
}
m_Branchcode = value;
}
}
/// <summary>
/// ColumnName:Branchname
/// Data Type:VarChar
/// Length:50
/// </summary>
public string Branchname
{
get
{
return m_Branchname;
}
set
{
if (value.Length > 50)
{
                    throw new InvalidData("The Branch Name  is more length", "Payroll", MessageBoxButtons.OK, MessageBoxIcon.Warning);
}
m_Branchname = value;
}
}
/// <summary>
/// ColumnName:Address
/// Data Type:VarChar
/// Length:50
/// </summary>
public string Address
{
get
{
return m_Address;
}
set
{
if (value.Length > 50)
{
                    throw new InvalidData("The Address  is more length", "Payroll", MessageBoxButtons.OK, MessageBoxIcon.Warning);
}
m_Address = value;
}
}
/// <summary>
/// ColumnName:Phoneno
/// Data Type:nVarChar
/// Length:20
/// </summary>
public string Phoneno
{
get
{
return m_Phoneno;
}
set
{
m_Phoneno = value;
}
}
/// <summary>
/// ColumnName:Emailid
/// Data Type:VarChar
/// Length:50
/// </summary>
public string Emailid
{
get
{
return m_Emailid;
}
set
{
if (value.Length > 50)
{
                    throw new InvalidData("The Emailid  is more length", "Payroll", MessageBoxButtons.OK, MessageBoxIcon.Warning);
}
m_Emailid = value;
}
}
/// <summary>
/// ColumnName:Companylogo
/// Data Type:VarChar
/// Length:150
/// </summary>
public string Companylogo
{
get
{
return m_Companylogo;
}
set
{
if (value.Length > 150)
{
                    throw new InvalidData("The Companylogo  is more length", "Payroll", MessageBoxButtons.OK, MessageBoxIcon.Warning);
}
m_Companylogo = value;
}
}
        public string StdCode
        {
            get
            {
                return m_StdCode;
            }
            set
            {
                if (value.Length > 20)
                {
                    throw new InvalidData("The StdCode is more length", "Payroll", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                }
                m_StdCode = value;
            }
        }
        public string LandLine
        {
            get
            {
                return m_LandLine;
            }
            set
            {
                if (value.Length > 20)
                {
                    throw new InvalidData("The LandLine is more length", "Payroll", MessageBoxButtons.OK, MessageBoxIcon.Warning);
                }
                m_LandLine = value;
            }
        }
public bool Insert ()
{
dalObj.Insert(this);
return true;
}
        public bool Update()
        {
            dalObj.Update(this);
            return true;
        }
        public void get()
        {
            dalObj.get(this);
        }
}
}


//Presentation Layer
 BOL.bolCompanyDetailsMaster mcd = new PayRoll.BOL.bolCompanyDetailsMaster();
                    mcd.Branchcode = txtbranchcode.Text;
                    mcd.Branchname = txtbranchname.Text;
                    mcd.Address = txtaddress.Text;
                    mcd.StdCode = txtStdCode.Text;
                    mcd.LandLine = txtLandline.Text;
                    mcd.Phoneno = txtmobileno.Text;
                    mcd.Emailid = txtemailid.Text;
                    mcd.Companylogo = destFileName;
                    mcd.Insert();
                    MessageBox.Show("Record Saved Successfully", "Payroll", MessageBoxButtons.OK, MessageBoxIcon.Information );


My problem is not update the data into Ms Access Database