window.debug.isDebug is null or not an object

I have user control which contains UpdatePanel. For UpdatePanel I have tried to put UpdatePanelAnimationExtender, but there's coming javascipt error which says "window.debug.isDebug is null or not an object". Without UpdatePanelAnimationExtender UpdatePanel is working great. I'm using ASP.NET 2.0 and latest AJAX Framework and ControlToolkit. What could be wrong?

Thanks
juster

You likely have old scripts from an AJAX CTP or Beta cached on your web server or on your browser. Reset IIS and make sure you do a CTRL-F5 on your browser.

window.debug.isDebug is null

While using updatepanel, I'm getting a javascript error window.debug.isDebug is null. Though updatepanel gets updated, some events like ajaxcontroltoolkit's updatepanelanimation etc. are not working. I am experiencing this problem only in machine where AJAX Futures December CTP was installed. Before installing AJAX I have removed all previous ajax versions also. Anyone else met with the same kind of error?

Maybe your AjaxToolkit isn't newest,The newest version haven't the problem.