It's because you use either it's own remote or ARC control from your TV via it's hdmi ARC port.
If your tv is old it won't have an arc connection, all new large sets have them, they usually need to be activated in the menue. Some have an HDMI in and out and are controlled via ARC in the newer cable boxes.
What TV model?
What cable box/dvr model?
Any Blu ray device ?
Are you using decent V1.4 HDMI cables?
Is this an old SB 1 or the newer SB 1 Plus?
Are you trying to use bluetooth?
Does it have an hdmi in and out port? Photos of the SB1 don't show the I/o panel...
your old plasma won't work... , to use it's volume control you need to either use it's vairable audio output or earphone jack.
I doubt it has coaxial or optical audio outputs...
You won't, You need to either use ARC on HDMI out of the cable box or DVR and to set the cable box to variable audio out and change the remote from TV volume to Cable box volume control.. Audio should be in sync if you're using a compoonent connection and use the r/w RCA jacks on the box. Or use the optical/coax audio connection.
You either get hdmi's ARC option to work (only a couple boxes support it) or use variable audio out of the cable box. Or use the TV's variable audio out or headphone jack. Optical or Coaxial audio might not be variable. You need to go into the boxes audio setup to change "fixed to Variable" If the TV also has a blu ray connected, you have to use the tv's variable output. However I doubt the rc122 can change the old tv's inputs...