On slush's pool you must have a seperate worker for each device on each pc. For instance I have it set up so I use USERNAME.main for my main PC and USERNAME.dedminer for my dedicated miner's first gpu and USERNAME.dedminer2 for my dedicated miner's second gpu and USERNAME.dedminerc for my dedicated miner's cpu. Also know that average hashes on slushes pool are by round. I don't know how long a round is, but when I go from a dead stop for a few days due to being away to mining full power, it takes anywhere from 14-18 hours before I end up seeing my total hash rate as the average hash rate. I hope this helps

Halix