To assign the optical input, follow these steps:
Turn your TV on and select the correct video input to view the System menu
on the remote, press system
press the right arrow to highlight the "media center" icon at the top of the menu
press the down arrow to highlight "optical source"
press the right arrow, then the up arrow or down arrow to select the input that is using the optical connection ("tv," "cbl∙sat," "vcr" or "aux")
Note: If you are not using the VS-2 video enhancer accessory, check to be sure that the input selected matches the one you are using: TV, CBL∙SAT, VCR or AUX.