[Solved] All CheckBoxes Checked in ASP.Net GridView Row

I have a GridView with a CheckBox on each row, but when i save the checked state it thinks all CheckBoxes are checked when only the first row is help please

<asp:GridView ID="gvStaff" runat="server" AutoGenerateColumns="False" BackColor="#DEBA84" BorderColor="#DEBA84" BorderStyle="None" BorderWidth="1px" CellPadding="3" CellSpacing="2" DataSourceID="dsStaff" Style="z-index: 1; left: 4px; top: 37px; position: absolute; width: 296px" AllowPaging="True" PageSize="8" ShowHeaderWhenEmpty="True" DataKeyNames="Id" Height="20px">
    <EmptyDataTemplate>
        <div align="center">No records found.</div>
    </EmptyDataTemplate>
    <Columns>
        <asp:TemplateField>
            <ItemTemplate>
                <asp:CheckBox ID="chkSelectCode" runat="server" />
            </ItemTemplate>
            <HeaderStyle HorizontalAlign="Left" />
        </asp:TemplateField>
        <asp:BoundField DataField="StaffNo" HeaderText="StaffNo" SortExpression="StaffNo" Visible="False" />
        <asp:BoundField DataField="fulln" HeaderText="Name" SortExpression="fulln">
            <HeaderStyle HorizontalAlign="Left" />
        </asp:BoundField>
    </Columns>
</asp:GridView>

Private Shared objALCode As New ArrayList()
Private Sub SaveCheckedStatesCode()
    Dim rowIndex1 As Integer = -1
    For Each row As GridViewRow In gvStaff.Rows
        rowIndex1 = Convert.ToInt32(gvStaff.DataKeys(row.RowIndex).Value)
        Dim isSelected1 As Boolean = CType(row.FindControl("chkSelectCode"), CheckBox).Checked
        If ViewState("SELECTED_ROWSCode") IsNot Nothing Then
            objALCode = CType(ViewState("SELECTED_ROWSCode"), ArrayList)
        End If
        If isSelected1 Then
            If Not objALCode.Contains(rowIndex1) Then
                objALCode.Add(rowIndex1)
            End If
        Else
            objALCode.Remove(rowIndex1)
        End If
    Next row
    If objALCode IsNot Nothing AndAlso objALCode.Count > 0 Then
        ViewState("SELECTED_ROWSCode") = objALCode
    End If
End Sub