Drop down list Box

Hi Experts,

I I have three values in drop down list box with values like A, B, C.

Then I selectd "B" from the drop down box. But its not trigger any Event. I need the code for that. Or after selecting the List box value user press enter, Then the event should triggered.

Event trigger means I set break-point in DO_Handle_Event. So after selecting the List box value the system should goes to debugging mode.

Its very very urgent. Please help me on this issue.

I will reward full points.

Thanks.