checkbox in gridview (updatepanel)

[met0555]

Hi,

I have a grdiview with checkbox both are in an updatepanel.
What i'm trying to do is whenever a checkbox is clicked i want my labelbox to show +1 and when it's unchecked i want to show -1 .
The problem i'm having is i can't access that check box, it doesn't recognized it when i start writing checkbox2 ...... my code looks like this :

<asp:UpdatePanel ID="UpdatePanel1" runat="server">
                   <ContentTemplate>
                <asp:GridView ID="GridView1" runat="server" AllowPaging="True"    OnRowDeleting="GridView1_RowDeleting" OnRowEditing="GridView1_RowEditing" 
                          onrowupdating="GridView1_RowUpdating" 
                          onrowcancelingedit="GridView1_RowCancelingEdit" 
                    AllowSorting="True"     AutoGenerateColumns="False" DataKeyNames="ID" PageSize="20" 
                    style="font-size: 7pt; font-family: Tahoma" UseAccessibleHeader="False">
                    <Columns>
                     <asp:TemplateField ShowHeader="False">
                <ItemTemplate>
                 <asp:CheckBox ID="CheckBox2" runat="server" />
           </ItemTemplate>
            </asp:TemplateField>
                        <asp:CommandField CancelText="C" DeleteText="D" EditText="E" InsertText="I" 
                            NewText="N" SelectText="S" ShowDeleteButton="True" ShowEditButton="True" 
                            UpdateText="U"  />
                  
 
 
                      <asp:TemplateField HeaderText="ID" Visible="False">
           <EditItemTemplate>
            <asp:TextBox ID="textID2" runat="server" Text='<%# Bind("ID") %>' Width="28" Font-Size="8" Font-Names="tahoma" Enabled="False"></asp:TextBox>
                </EditItemTemplate>
                <ItemTemplate>
                    <asp:Label ID="Label15" runat="server" Text='<%# Bind("ID") %>'></asp:Label>
                </ItemTemplate>
            </asp:TemplateField>
.....

thanks