Use the debugger to see what your code is doing and what it is "not working properly".
The debugger allow you to follow the execution line by line, inspect variables and you will see that there is a point where it stop doing what you expect.
Debugger - Wikipedia, the free encyclopedia
Mastering Debugging in Visual Studio 2010 - A Beginner's Guide
The debugger is here to show you what your code is doing and your task is to compare with what it should do.
When the code don't do what is expected, you are close to a bug.