Jaxson:Depends on where you are getting it from. I can guarantee it's not from the terrestrial EIT service.
From the MythTV wiki:-
My Listings grabber is set to "Over-the-air" guide (EIT)
Default for the option below option is "not checked" but on mine it is "Checked" and working fine. (And so are others)
Perform EIT scan, Not Checked
If enabled, program guide data for channels on this source will be updated with data provided by the channels themselves 'Over-the-Air'. This is a choice to be made depending on the reliability of over the air data. There is the potential for getting last minute program updates if this is reliable.