What pool are you trying to mine to?
www.lbrypool.com is pretty good and has 0% fee's currently so you get 100% of the profits from you miner.
What you might be seeing is that the pools work out your hashrate based on the number of shares you submit and at what difficulty, if you have too high a difficulty then you will not submit as many shares.
The actual number of shares submitted doesn't matter; they are calculated against difficulty.
The ideal target is to have the least number of shares needed to have your machine recognized online and at the correct hashrate by the pool.
This will give the least number of rejects and discards.