They are hooked to the tv.
I should disconnect optical cable from the box and put it in the tv?
Does your TV have an optical output? If it does, then most TVs that I have seen will output the audio for your selected source on that optical output. If it doesn't have optical, then does it have 3.5mm or Red/White RCA outs that could plug into the transmitter?
Be sure you use the TV optical OUTPUT, not an INPUT, to run to the headphone transmitter.
Note that most TV optical outputs will downmix the ouput to Stereo Left/Right ONLY, but for your setup and for headphones that should be a moot point--seems like you only listen in stereo anyway, right?