OnAuthenticate doesn't fire within UserControl

Hi,

 

I try to accomplish the following:

 

The mainpage contains two items:

- a button

- a usercontrol

 

The usercontrol is placed inside an updatepanel so it can be altered using ajax.

 

I want to replace the usercontrol with another when the button is clicked.

 

Initially the usercontrol "MainPage.ascx" is loaded.

When the Button is clicked, it is replaced with the usercontrol "LoginControl.ascx"

 

So far no problem. The problem is that the "OnAuthenticate event" inside the LoginControl.asc not is fired.

 

Why is that?

And what can I do about it?

 

regards,

Martin

PS I can provide a small demo
...