two components with the same id can't be added to the application

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Hi all,

I have a ASP.net VB 2.0 application with AJAX Control Toolkit (updated just
some minutes ago to latest 10618 from 18. June 2007). Initially everything
works fine: I have an overview page, click on a link and a new window opens.
Within the new window I have another button where a new child-window opens
(by using JavaScript). In the child window I make a selection and click "OK".
The child window closes and my parent window will be updated automatically.
But now an error appears saying:

"Two components with the same ID
'ctl00_PlaceHol derMain_Initiat orSelectionExte nder' can't be added to the
application." (Screenshot:
http://img218.imageshack.us/img218/1...hsameidwk7.jpg)

As said the initial load works fine, problem just appears after closing the
newly opened child-window and the following update of the parent window. I
use several AJAX Controls on my page (3 ListSearchExten der, 2
CalendarExtende r, 2 MaskedEditExten der and 4 Animation Extender), the
"InitiatorSelec tionExtender" is a listSearchExten der.
Of course I've searched the net for this problem and found some interesting
pages, but:
(http://www.codeplex.com/AtlasControl...rkItemId=10945) ListSearchExten der does not have this.id
(http://forums.asp.net/p/1094818/1649900.aspx) My Extenders are not hidden.

Any ideas?

Many thanks!!