A single check box to check/uncheck all checkbox in a datagrid view

[johnsonlim026]

Hi,
I am a new bee in ASP.NEt.
My coding is as below.I have a problem in checking whether the first checkbox is checked or unchecked and then check /unchecked all the other checkbox in the datagridview.

<script runat="server">

    Sub CheckAll_Click(sender As Object, e As EventArgs)
        Dim i As Integer
        
        For i = 0 To dgv1.Rows.Count - 1
            
            CType(dgv1.Rows(i).FindControl("chkAll"), CheckBox).Checked = True
        Next
        
        
    End Sub

</script>


 <HeaderTemplate>								
                            <asp:CheckBox id="chkAllq" runat="server" OnCheckedChanged="CheckAll_Click" >
                            </asp:CheckBox>							
                            </HeaderTemplate>

My problem is how to fire the CheckAll_Click event when the checkbox is checked or unchecked.Does any one has idea on this?what should i put in instead of OnCheckedChanged as does not fire the event ?