crazy diamond 57

I never get the right amount of winning credits from the free credits every 4 hours. I’ve been keeping an eye on it and I get 20 instead of the 100 and I might get 80 instead of the 500 and so forth but I never get the right amount. I just noticed it a couple weeks ago but I’ve been playing this keno game for years. My sister has too but she always gets the right amount.