Run time error in Modal popup extender

whe开发者_JAVA技巧n im using modal popup extender in asp.net pages i got "Microsoft JScript runtime error: '_popupElement.parentNode' is null or not an object" this is run time error every time. does anybody know the overcome this problem.

this is my modalpopup tag

Remove the Visisbilty = "false" attribute for the target Panel control. The modal popup will handle visiblity for you. Additionally check the page codebehind to NOT set the visibilty to false of the target Panel. Let the pop-up do the magic!