A control cannot modify its parents' control collections.

Hey all..

Here is the situation:

I have a user control that has some nifty show/hide functionality that I need all over the place... I want a developer to add this control to their page, then set a property which is the ID of a panel control that they have elsewhere on their page....

When the page loads, i take the ID of that panel they passed to the property of my user control, and i want to do a controls.add to my user control, so that i can do the show/hide stuff to it...

when i run the code, i get the following error: A control cannot modify its parents' control collections.

I read somewhere that using placeholders would resolve this issue, but it hasnt.

Any ideas?

Thanks,
-md