Solera Senior Android Engineer interview questions

1 Phone screening with the HR with a couple of technical a,b,c questions. Followed by a technical exercise (small app) to complete in 1 week and submit the result on a Git repository. I've written the small app using Google CodeLab guides as accurate as possible. They rejected me stating that they found "inconsistencies in the code" and "discrepancies". I double-checked the code and there are no such things in it. It is exactly like any code in Google CodeLabs looks like .