Checkbox on Datagrid for ASP - asp.net

Question

I have a data grid on my project with a Checkbox as a TemplateField; but I can't acces the checkbox.checked property. Does anyone have any idea?
My ASP code:
<asp:GridView ID="GVP" runat="server" AutoGenerateColumns="False" DataSourceID="DSP">
<Columns>
<asp:TemplateField HeaderStyle-Width="5%" ItemStyle-Width="5%" FooterStyle-Width ="5%">
<ItemTemplate>
<asp:CheckBox ID="SelectCb" runat="server"></asp:CheckBox>
</ItemTemplate>
<FooterStyle Width="5%"/>
<HeaderStyle Width="5%"/>
<ItemStyle Width="5%"/>
</asp:TemplateField>
<asp:BoundField DataField="Answers" HeaderText="Options" SortExpression="Answers" />
</Columns>
</asp:GridView>
My VB code behind:
Protected Sub Button1_Click(ByVal sender As Object, ByVal e As System.EventArgs) Handles buttonNext.Click
Dim SelectedBox As Boolean = False
For Each row As GridViewRow In GVP.Rows
Dim cb As CheckBox = row.FindControl("SelectCb")
If cb IsNot Nothing AndAlso cb.Checked Then
SelectedBox = True
Dim RID As Integer = Convert.ToInt32(GVP.DataKeys(row.RowIndex).Value)
Else
ShowMessage("You did not select anything")
End if

Answer 1

try this:
For Each row As GridViewRow In gvTest.Rows
Dim cb As CheckBox = row.FindControl("SelectCb")
If (CType(row.FindControl("SelectCb"), CheckBox)).Checked = True Then
SelectedBox = True
Dim RID As Integer = Convert.ToInt32(gvTest.DataKeys(row.RowIndex).Value)
End If
Next

Answer 2

It's hard to tell what you are trying to do here and how you are testing but my guess is that this is because you are not checking for row type. So the first row is actually the header and therefore will not have a checkbox at all (and you will get the message).
For Each row As GridViewRow In GVP.Rows
If row.RowType = DataControlRowType.DataRow Then
Dim cb As CheckBox ...

Answer 3

The problem really resided on the Page_Load where I was binding the grid to the datasource; I deleted it and the problem was solved.