Commented Unassigned: UpdatePanelAnimationExtender - Object reference not set to an instance of an object [27979]

Hi,

When I try to use UpdatePanelAnimationExtender I'm always getting the error Object reference not set to an instance of an object.
My project worked fine until I updated Ajax Control Toolkit to version 15.1.4

Thank you,
Comments: I found the factor that caused this error: your UpdatePanel has asp:PostBackTrigger, but UpdatePanelAnimationExtender needs asp:AsyncPostBackTrigger. You can see [here](https://ajaxcontroltoolkit.codeplex.com/SourceControl/latest#AjaxControlToolkit/UpdatePanelAnimation/UpdatePanelAnimationExtender.cs) that UpdatePanelAnimationExtender casts every trigger to AsyncPostBackTrigger in the OnPreRender method, so using AsyncPostBackTrigger is the only way of resolving this problem.