dropdownlist in gridview

Form.aspx::::::::

protected void GrdvewBnkDetls_RowDataBound(object sender, GridViewRowEventArgs e)//rosna
{
Trace.Write("ADMIN.Master.frmPartySupplier_Customer.GrdvewBnkDetls_RowDataBound");

if (e.Row.RowType == DataControlRowType.DataRow)
{
if (e.Row.RowIndex != -1)
{
protected void btnAddBnkDtls_Click(object sender, EventArgs e)//rosna
{
Trace.Write("ADMIN.Master.frmPartySupplier_Customer.btnAddBnkDtls_Click");
DataTable dt = blSupplierObj.BindBnkDtlsGrid(ref GrdvewBnkDetls);
DataRow dr = dt.NewRow();
//dr["BankName"] = "";
//dr["Branch"] = "";
//dr["Account"] = "";
dt.Rows.Add(dr);
ViewState["dtBnk"] = dt;
rowid = 0;
GrdvewBnkDetls.DataSource = dt;
GrdvewBnkDetls.DataBind();


}
e.Row.Cells[0].Text = Convert.ToString((e.Row.RowIndex + 1));
DropDownList ddlBank = (DropDownList)e.Row.FindControl("ddlBnkNme");
ddlBank.DataSource = dtBankDetails;
ddlBank.DataTextField = "Name";
ddlBank.DataValueField = "Uoid";
ddlBank.DataBind();
DataTable dt = (DataTable)ViewState["dtBnk"];
if (dt != null)protected void ddlBnkNme_SelectedIndexChanged(object sender, EventArgs e)
{
Trace.Write("ADMIN.Master.frmPartySupplier_Customer.ddlBnkNme_SelectedIndexChanged");

DropDownList ddlbnk = (DropDownList)sender;
GridViewRow row = (GridViewRow)ddlbnk.NamingContainer;
DropDownList ddlT = (DropDownList)row.FindControl("ddlBrnch");
/// blSupplierObj.GetBankDetails("CFN_Bank");

if (ddlbnk.SelectedValue != "0")
{
BLPage.FillDropDown(ref ddlT, "Uoid", "Name", "SELECT Uoid,Name fROM CFN_TB_BankBranch Where FK_BankID ='" + ddlbnk.SelectedValue + "' ");
}


}
{
if (rowid < dt.Rows.Count)
{
ddlBank.SelectedValue = dt.Rows[rowid]["BankName"].ToString();
}
if (ddlBank.SelectedValue != "0")
{
DropDownList ddlBranch = (DropDownList)e.Row.FindControl("ddlBrnch");
blSupplierObj.BindCombo(ref ddlBranch, "Uoid", "Name", "SELECT Uoid,Name fROM CFN_TB_BankBranch Where FK_BankID ='" + ddlBank.SelectedValue + "' ");
if (dt.Rows[rowid]["Branch"].ToString() != "0")
ddlBranch.SelectedValue = dt.Rows[rowid]["Branch"].ToString();
}
DropDownList ddlAcount = (DropDownList)e.Row.FindControl("ddlAccnt");
ddlAcount.DataSource = dtAccount;
ddlAcount.DataTextField = "Name";
ddlAcount.DataValueField = "Uoid";
ddlAcount.DataBind();
//if (dt.Rows[rowid]["Account"].ToString()!= "0" && !string.IsNullOrEmpty(dt.Rows[rowid]["Account"].ToString()))
//if (dt.Rows[rowid]["Account"].ToString() != "" && rowid // ddlAccount.SelectedValue = dt.Rows[rowid]["Account"].ToString();
//rowid++;

string str = DataBinder.Eval(e.Row.DataItem, "Account").ToString().Trim();
if (str != "")
{
ddlAccount.SelectedValue = str;
}


}
else
{
DropDownList ddlAcount = (DropDownList)e.Row.FindControl("ddlAccnt");
ddlAcount.DataSource = dtAccount;
ddlAcount.DataTextField = "Name";
ddlAcount.DataValueField = "Uoid";
ddlAcount.DataBind();
}
}
}
}

protected void GrdvewBnkDetls_RowCommand(object sender, GridViewCommandEventArgs e)//rosna
{
Trace.Write("ADMIN.Master.frmPartySupplier_Customer.GrdvewBnkDetls_RowCommand");
GridViewRow objGridViewRow = (GridViewRow)((ImageButton)e.CommandSource).Parent.Parent;

if (e.CommandName == "onDelete")
{
DataTable dt = blSupplierObj.BindBnkDtlsGrid(ref GrdvewBnkDetls);
if (dt.Rows.Count > 0)
{
int id = int.Parse(objGridViewRow.Cells[0].Text);
BL_PartySupplier_Customer.Tablefilter(ref dt, " RowID <> " + id.ToString());
rowid = 0;
GrdvewBnkDetls.DataSource = dt;
GrdvewBnkDetls.DataBind();
ViewState["dtBnk"] = dt;


}
else
{
}
}
}


BL_Form.aspx


public string GetBankDtils(ref GridView GrdvewBnkDetls, string buttonText, ENT_PartySupplier_Customer entbnkObj)
{
//...
StringBuilder strQuery = new StringBuilder();
string strQuerys = string.Empty;
if (GrdvewBnkDetls.Rows.Count >= 1 &&
(GrdvewBnkDetls.Rows[0].FindControl("ddlBnkNme") as DropDownList).SelectedValue != "0")
{
for (int i = 0; i < GrdvewBnkDetls.Rows.Count; i++)
{
//--
strQuery.Append(" SELECT ");
strQuery.Append("'" + Guid.NewGuid() + "',");
strQuery.Append("'" + (GrdvewBnkDetls.Rows[i].Cells[1].FindControl("ddlBnkNme") as DropDownList).SelectedValue + "',");
strQuery.Append("'" + (GrdvewBnkDetls.Rows[i].Cells[2].FindControl("ddlBrnch") as DropDownList).SelectedValue + "',");
strQuery.Append("'" + entbnkObj.PartyUoid + "',");
strQuery.Append("'" + (GrdvewBnkDetls.Rows[i].Cells[3].FindControl("ddlAccnt") as DropDownList).SelectedValue + "',");
strQuery.Append("'" + Guid.NewGuid() + "',");
strQuery.Append("'" + clsCommon.convertDate(DateTime.Now.ToString("dd/MM/yyyy")) + "',");
strQuery.Append("0");
strQuery.Append(" UNION ALL ");

}
strQuerys = strQuery.ToString();
}


else
{
strQuerys = string.Empty;
}

if (strQuerys != string.Empty)
{
int x = strQuery.ToString().Length;
strQuerys = strQuerys.Remove(strQuery.ToString().Length - 11, 11);

}

return strQuerys;
}
//...

 public void gvInitialBankLoad(ref GridView GrdvewBnkDetls)
        {
            Trace.Write("UniERP.ADMIN.BL.Master.BL_Company.gvInitialCustomLoad");
            DataTable dt = fillBankColumns();
            DataRow dr = dt.NewRow();
            dr["RowID"] = 1;
            dt.Rows.Add(dr);
            GrdvewBnkDetls.DataSource = dt;
            GrdvewBnkDetls.DataBind();

        }


public DataTable BindBnkDtlsGrid(ref GridView GrdvewBnkDetls)
{
Trace.Write("UniERP.ADMIN.BL.Master.BL_Company.BindCustomPropertyGrid");

DataTable dt = fillBankColumns();

for (int i = 0; i < GrdvewBnkDetls.Rows.Count; i++)
{
DataRow dr = dt.NewRow();

dr["RowID"] = GrdvewBnkDetls.Rows[i].Cells[0].Text;
dr["BankName"] = ((DropDownList)GrdvewBnkDetls.Rows[i].Cells[1].FindControl("ddlBnkNme")).SelectedValue;
dr["Branch"] = ((DropDownList)GrdvewBnkDetls.Rows[i].FindControl("ddlBrnch")).SelectedValue;
dr["Account"] = ((DropDownList)GrdvewBnkDetls.Rows[i].FindControl("ddlAccnt")).SelectedValue;
dt.Rows.Add(dr);
}
return dt;
}

private DataTable fillBankColumns()
{
Trace.Write("UniERP.ADMIN.BL.Master.BL_PartySupplier_Customer.fillBankColumns");

DataTable dt = new DataTable();
DataColumn dc = new DataColumn("BankName", typeof(string));
dt.Columns.Add(dc);
dc = new DataColumn("RowID", typeof(Int32));
dt.Columns.Add(dc);
dc = new DataColumn("Branch", typeof(string));
dt.Columns.Add(dc);
dc = new DataColumn("Account", typeof(string));
dt.Columns.Add(dc);
return dt;
}

problem is adding a new row..first row value cleared

Populate the DropDownList2 in SelectedIndexChanged of your DropDownList1.