Need help with my Litcoin Minner

I was wandering if anyone could help me with my GPU minner. I have a Sapphire Radeon HD 7850 2GB. I use reaper to mine for Lite coins. My problem is that I am having is when I mine, I am only getting max 6 Kh/s. I thought my card was able to get around 300?

Here's what my litecoin.conf looks like

port 9332

protocol litecoin

worksize 256
aggression 13
threads_per_gpu 1
sharethreads 18
lookup_gap 2
gpu_thread_concurrency 10244

Thanks for the help