OK, it's most likely that your hashrate is too low for the p2pool difficulty. From the p2pool documentation:
Q: Why does my miner say it has found a lot of shares but p2pool say I have only found a few?!
A: The real P2Pool difficulty is hundreds of times higher than on normal pools, but p2pool essentially lies to your miner and tells it to work on relatively easy shares so that it submits shares every few seconds instead of every few hours. P2Pool then ignores any submitted shares that don't match the real share difficulty. By doing this, P2Pool can more accurately report your local hash rate and you can see if you are having problems with too many stale shares quickly
With your hashrate, it might take a long time to get a share that qualifies for the minimum difficulty of the p2pool.
There are currently other miners on here and they are generating coin, but that's because their hashrate is much higher too.