Breakpoint not hitting

Question

I have put a breakpoint, but it is not hitting. when i place cursor on the breakpoint i can see. at(filename.cs,line no) The breakpoint will not currently be hit. No symbol have been loaded for this document. what might be the problem. searched other forums got a one point, is that all the filenames in the folder and subfolder of the application must be unique. my application contains unique file names. but the breakpoint is not hitting. and also my pages contains usercontrols. Is this a problem. any help , is appreciated thanks in advance. Uday