Hell if I know. What client are you using and do you belong to a mining guild? If you're seeing numbers processed then it is working.
Also, remember while doing this that your video card is running at full power 100%. It's going to be generating a lot of heat and using a lot of power. I have to have an air conditioner and fan blowing on my computer constantly to keep it idling at a "cool" 72°C.
I'm just using the regular bitcoin client and it's only showing these tiny blocks at the bottom which I don't know what they do.
I tried using DiabloGPU but I set the IP as my regular IP and the port as 80 (well, just common sense. Hope it's right) and it gave me connection refused errors until finally it showed a hashcount and my computer nearly crashed and my gpu diode's temperature skyrocketted to 73º. I'm assuming that means it wasn't working correctly.
I read somewhere that I needed something like bitcoin -server or bitcoind but the instructions were written by linux experts taking about stuff like rebuilding a kernel and editting config files which I don't know a damn stuff about.
I have a feeling part of the difficulty is because I'm trying to do this on a mac.