multiple usecontrols accessing another usercontrol inside update panel ..problem

In my application i am showing 2 usercontrols as modelpopup from my Main aspx page.
That 2 usercontrols again accessing one common usercontrol,which is having checkbox selection
in javascript.
From my aspx page if i display first usercontrol as modelpopup that checkbox selection is working fine.
But from second usercontrol 'Object required' error is coming.

In my main aspx page i am keeping that usercontrols in updatepanel.In my case i update
panel is mandatory...

anybody knows a solution.From past 2 weeks i am searching for the same

thanks in advanc