Recently I tried debugging java script code which is called on ribbon button click. But i am not able to debugger that code. I am able to debug javascript on form level. But not on Ribbon button level. Looks strange!!
I tried solution provided in this forum post , but its partially resolved debugging issue.
After digging deep, I tried upgrading IE version from IE8 - IE9. Finally debugging issue on ribbon button click has been resolved.
Hope it will be helpful!!!