I just got my Samsung HP-T4254 Plasma TV, and hooked it up via a Monster HDMI cable to the Scientific Atlanta Explorer 4250HD cable box. I followed the instructions to set up the cable box remote's volume controls. After doing so the mute button works. However, the volume + and - controls don't work. When I use them I see the volume bars go up and down on the screen. But the volume doesn't get any louder or softer. The only way I can control the vol right now is with the TV's remote. Is there any known fix for this? I would like to use the cable box's remote to control the volume.

Thanks

Unlikely. Generally, the digital audio outputs are not controlled by the RC of the STB. One possibility is to use the separate analog output cables to your TV and keep the HDMI for video only. Of course, that limits you to stereo sound.