Lose the Ajax-SliderExtender after Page Refresh (F5)

I'm using a Ajax SliderExtender in a UpdatePanel. I set a BehaviorID and call $find('behavorID').add_valueChanged function in the $document.Ready. Everything is fine but when I press F5 and refresh the page, I lose the slider in a 1/3 (wtf) chance. If I set var slider = $find('behavorID'), it recognises slider is null.

I've run it in C开发者_JAVA技巧hrome, IE8 and met the same problems.

Any ideas? solutions?

Regards

didn't find solution. I used jquery slider instead.