Reference a control within a Form view for a Update Panel Trigger?

I am attempting to Use a UpdatePanel to refresh one of the formviews within my page when the update button is clicked but I get the following error when running the page.
A control with ID 'btnReportUpdate' could not be found for the trigger in UpdatePanel 'upnlReportForm'.
.

Is there another method to accomplish this.

Thanks

That's usually because the control you try to reference, is a part of a template of another control. Are you sure that you need to add it as a trigger? Perhaps try posting at least a part of your code, so that we can have a look