CheckBoxList in TemplateField/ItemTemplate

Question

Hello All, 

I am using a CheckBoxList/ItemTemplate/FieldTemplate/GridView as below:

<asp:GridView ID="GridView1" runat="server"  

    AutoGenerateColumns="False"  

    GridLines="Both"  

   CssClass="mGrid" 

   PagerStyle-CssClass="pgr"  

    AlternatingRowStyle-CssClass="alt">

<AlternatingRowStyle CssClass="alt"></AlternatingRowStyle>

    <Columns>  

            <asp:TemplateField HeaderText="Check Box"> 

            <ItemTemplate>

                <asp:CheckBoxList ID="CheckBoxList1" runat="server">

                    <asp:ListItem></asp:ListItem>

                </asp:CheckBoxList>

            </ItemTemplate>

            </asp:TemplateField>

    </Columns>  

  <PagerStyle CssClass="pgr"></PagerStyle>   

</asp:GridView>

Codebehind should be:

If ( ALL the checkboxes in GridView1 are checked),
{
        continue. 
}
Else
        Message Box saying "Please Check the missing CheckBoxes". End

How to achieve this?