Created Unassigned: ModalPopupExtender.show() doesn't works in AsyncFileUpload_UploadedComplete [27741]

Hello.

In a WebPage, I'm using an AsyncFileUpload. In the event UploadedComplet, I'am tring to show a ModalPopupExtender, But this don´t show. If, I use to the ModalPopupExtender into other event, it show the popup without problem.

I'am using the AjaxControlToolKit 4.1.7.12.13 with ASP.Net 4.0.

Thank you.