SelectedIndexChanged

Question

first off... sorry this is probably a stupid question but i cant find the info i need. C# Web project created in VS 2003 Two list boxes, the first one has a list of groups (lstgroups) from the AD which works fine, when one is selected i would like it to list the members of the group in the second listbox (lstusers). I created the code and tossed it under the correct event (did the properties of lstgroups, methods, double clicked the SelectedIndexChanged and it creates the function) tossed my code in there and loaded the page. it lists the groups, i select one, doesnt update. I tossed this code in a button and it works great. what am i missing? Sorry, Thanks Justin