Some times, you get frustrated because your code doesn't work when it calls methods from other people such as framework. also you don't have source code of the methods. so, even with the reference, it is not easy to understand what is wrong. Well then, open the assembly and look into the IL code with ILDasm.
If you have little knowledge of x86 assembly code, you probably can recognize the similarity in IL code. so, you will be able to understand what could be cause of your problem.