Tvheadend

TVTime shows that all my inputs are working fine, and TVheadend has my ATSC channels working fine as well. I wanna be able to take my S-Video input and also broadcast it as well. TVheadend does see two capture cards from my HVR-1800 but I tried adding a service and giving it a name, but nothing comes up when I try to watch this channel. Nothing but a black screen.

Was the frequency suppose to be set as well?