I wonder why, try to use cgminer, I am having the same thing too, my miner is showing 610 mega hashes, but in the pool it is showing fewer, I think it is something with the script calculating the mega hashes. Follow what the miner says . What the miner says is the real power, and maybe our calculations are right...

I really thank you ! I hope it grows more and more, I have already 22 signed up, let's wait and see what power we will reach.
Thanks again