Where are you mining?
Probably
http://mining.bitcoin.cz, since he said Slush pool. Anyway, 15 and 163 shares isn't that much. To get real money from mining, you would need to invest a lot of money in hardware. Also, at slush's pool, you gain a lot more BTC when you find the shares in the end of the block than in the beginning of it. And one more thing, it can take some time for the rewards to update, so it could be that too.