Also, were these channels recently added by your cableco (or are they OTA)? If cable, it may take a while to populate the guide data. In my market and with my cableco, it typically takes 7-14 days.
If they're OTA, make sure you have the correct zip code plugged in your setup to get them.
"Wonderful things can happen when you sow seeds of mistrust in a garden of a**holes," -- Philosopher Raylan Givens