SatMex 5 doesn't have the best North American footprint. You might be marginal with that size dish. A quick way to provide answers to a few fundamental questions might be to see if you can lock on to 11820 V 30000. You won't scan in any channels; it's a HughesNet TP. However, it's going to have a stronger signal at your location than any of the television channels.
Try that, and provide a little more background: Is the dish motorized? Are you certain you are aligned properly? Have you had success receiving other nearby satellites?