how to access asp.net checkbox control in repeater for update panel trigger?

[PPowerHouseK]

i am using update panel. There are lots of checkbox in repeater and i wanna use update panel trigger but i didn't access checkbox control. how can i access it ?\[code\] <asp:UpdatePanel ID="up" runat="server"> <ContentTemplate> </ContentTemplate> <Triggers> <asp:AsyncPostBackTrigger ControlID="checkbox1" EventName= "CheckedChanged" /> </Triggers> </asp:UpdatePanel>\[/code\]