any messages in server log? which version you using?
The problem with the button is eliminated.
I don't know why, but the method will be called now.
The problem which isn't fixed is the problem with the panelGrid.
If i try the sample from the livedemo it works fine.
If i try the same with my tags, the two panels will be shown one below the other... And i dont know why...
I use 3.3.0...
please doublecheck that you didn't have any other childs for panelGrid except the panels. (in your code I see "...." and not sure whats there.)
you could also use FireBug for example in order to check the table generated by panel grind in DOM inspector.