runtime error: '_popupElement.parentNode' is null or not an object

Question

When I'm using modal popup extender in asp.net pages, I got this runtime error every time:

"Microsoft JScript runtime error: '_popupElement.parentNode' is null or not an object"

Does anybody know how to overcome this problem?

This is my modalpopup tag:

<asp:ModalPopupExtender ID="ModalPopupExtender1" runat="server" 
        PopupControlID="Panel3" TargetControlID="ImageButton1" 
             DropShadow="true"
             OkControlID="OkButton"
            OnOkScript="onOk("
             CancelControlID="CancelButton"  >
    </asp:ModalPopupExtender>

Answer 1

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!