Hi,
You may be unable to see the button click events firing on certain machines though it may work in some other machines.
Mostly when you are developing in your local system, the events do work well. But once you move the code to production, the button click events may not fire at all.
Please check http://aspnet_harish.blogspot.com/2005/04/button-click-events-not-firing-aspnet.html which explains the cause and resolution for the same.
Thanks.