AJAX updatable control

[chylu]

Hi

I'm developing a control that will start a background thread
(Backgroundworker) and will continously update it's progres.
Obviously i use UpdatePanel, and have there a label, where the progress
value shows and a button to start the action.

The problem is, that i need to click the button twice before the action
starts. The behavior is as follows:
Site is loaded
I click the button - nothing is happening
I click the button again - bip, it runs.

After many tries, a used following solution:

Control:
ScriptManager
UpdatePanel
Label
Button
/UpdatePanel

The button is explicitly connected to BusinessLogic and starts the action.

Page:
ScriptManager
UpdatePanel
MyAboveControl
Timer - to refresh the control
/UpdatePanel

Any sugestions will be appreciated. I've spent 2 days on it and still no
light in the tunnel...
The most important - it MUST be done as a web control.