Are those blocks confirmed?  In my tests for some of the coins it can take days before they are confirmed and enough liquidity exists to exchange them.  There is a LONG tail on some of them (not hours, days, maybe a week).  That said, in my tests the payouts eventually show up.  I think many people mine for a day and compare numbers, but thats not really a good comparison since many of the smaller alt coins won't have been paid yet.  Mine for 24 hours then look at your total payout 7 days later...