Uploaded code passing all test before I send it

Hi, I have problem with uploaded file in code challenge. After implementing instructed changes I compiled solution, debug it, even run all test and everything worked fine - solution was compiled, application run and all tests passed. I sent that solution (excluding bin/obj and packages directories - to met file size limitation) and I received message that some tests failed (without test passing/failing list so I assume that solution wasn't even succesfully compiled). I even tried to compile and re-run solution files 'after directories removal' (I was affraid that by mistake I removed important file), but all packages was downloaded correctly and soution work good. I don't have idea what else I should check or what I'm doing wrong. Is there any hint for similar situation?