Controling volume with cable remote

I'm not sure if anyone can help me with this problem, but here goes. I recently purchased my first hdtv and a speaker system with it. The speaker system is more like a pc speaker system with a volume control. When I originally hooked up the tv I was using the component cables and I was able to control the volume with my cablevision remote. Now that I've switched to the hdmi cable I have lost the feature to control the volume through the cable box. I have to use the volume control on the speakers. any ideas what I might need to do to solve this problem? It's a cablevision box and like I said when I used the component cable it worked fine with the hdmi the sound can't be controled.

any help or advice would be great.

If you need any additional info let me know as well.