Store Data Into Dropdownlist Inside GridView EditItemTemplate And FooterTemplate

[justhottest]

Is Anyone Encountered Error as Message Like This ==> ASP.NET Using CSharp Visual Studio 2008

"NullReferenceException was unhandled by user code"

Where I just want to Bind DropdownList that declared inside GridView?
Here where I Construct GridView
=======================================================
<asp:GridView ID="GridOne" runat="server" OnRowDataBound="dvg_RowDatabound" AutoGeneratedColumns="Fales">
<Columns>
<asp:TemplateField HeaderText="Code">
<EditItemTemplate>
<aspropDownList ID="DDL" runat="server" ></aspropDownList>
</EditItemTemplate>
</asp:TemplateField>
</Columns>
</asp:GridView>

================== The Code Behind =====================
protected void dvg_RowDatabound(object sender, GridViewRowEventArgs e)
{

if (e.Row.RowType == DataControlRowType.DataRow)
{

DataTable Dtb = Ds.Table[0];

DropDownList DDl1 = (DropDownList) e.Row.FindControl("DDl") as
DropDownList;


DDl1.DataSource=Dtb; << = Error Start Here as Above Error
Appear Message

DDl1.DataMember = "MyDataMember"
DDl1.DataValueField = "MyValue"
DDl1.DataBind();

}


}
=====================================================

[Hack]

Do you know what line is causing the error?