my dropdownlist can't break even i've placed breakpoint in the dropdownlistName_selectedIndexChanged

is there someone can help me with my problem??

i create a dropdownlist, named it ddlBookType, then i create the event handler ddlBookType_selectedIndexChanged, and then i place a breakpoint on that event handler in order to debug the function. but when i run the program, it doesn't break at all even when i keep changing the list in the dropdownlist.

help me...i'm stressout of this. i've try it all day.

thanx.