drop down box and list box

Hi Guys,
I have a drop down box that  is full of team ids. what i want is when user selects an id from the drop down the list box is populated (from the database) with the names of all members of the team. i tried using selectedIndexChaneged and textChanged events of the drop down but didn't work. the events are not fired somehow? is it ok? which event should i use? or any work around?
Thanks
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