I have 10 T3 Spyrooms, but no lock at all~

At first 5 spyrooms, I can farm plenty locks, but with the chain goes on and more green I have, fewer locks I can get. Worst thing is now, 10 T3 spyrooms and only 1 lock per run for 3 runs and no lock per run for last 2.

Is there someing wrong? I've asked frineds, they get least 2~3 locks per run.

Soneone please tell me please.