Java APIs

Hello everyone,
I am trying to decompile the classes in a jar file. I have already asked the creator of the classes if I can do this and he said yes, so I'm not trying to do anything unethical. I have tried a few java class decompilers (jad, JDec, JReversepro) and they all produce java code that can't be compiled: the java code has errors in it. I went over to sourceforge, and I have searched on the internet for java decompilers. There seems to be many decompilers out there. I was wondering has anyone ever decompiled classes with a perfect or almost perfect success? If so, what did you use? I'd rather just get a reliable decompiler than keep struggling with one fail after another.
I hope it is ok asking this question here. I know it kind-of goes against the idea in this part of the forums. ;)

Thanks for any help!
Vance