Well if you're talking about MikesPaid4Email then there's a good explanation why your referral earnings haven't increased in some days now (should work again tomorrow!) other programs I don't know about, surely some others might have problems in that area but if no one else is having problems and you know for sure that you should be getting some earnings from your downline, wait for few days and contact the webmaster and ask if there's some problems!
Oh and I'm not sure about the earnings from those days when they didn't add up, I think they're loost for good but not sure......
Pia