gridview event not firing in asp.net

See more:

ASP.NET

my gridview event not firing
i am doing like this

<asp:GridView CssClass="clsborder" runat="server" ID="grdDematChk"
AutoGenerateColumns="False" DataKeyNames="isincd" Width="100%"
BackColor="#7fb16c" BorderColor="#cccccc" BorderStyle="None" BorderWidth="1px"
CellPadding="0" CellSpacing="0" Height="1px" AllowPaging="true"
AllowSorting="true" PageSize="10"
OnRowEditing="grdDematChk_RowEditing"
OnRowCancelingEdit="grdDematChk_RowCancelingEdit"

OnRowUpdating="grdDematChk_RowUpdating" OnRowDeleting="grdDematChk_RowDeleting"
AutoGenerateDeleteButton="True" AutoGenerateEditButton="True" >

and in code behind
Protected Sub grdDematChk_RowEditing(ByVal sender As Object, ByVal e As GridViewEditEventArgs)
grdDematChk.EditIndex = e.NewEditIndex
GetAddModeDataView()
End Sub