Well I think it all depends.
For example: My house literally sits just within the 4g area and I get no signal... unless. I am upstairs right near the window. Outside, walking around, I get 4g coverage (albeit quite low of a signal).
If I may ask, are you within a building when you try. They may show 4g in your area but unless you have nothing above your head besides the baby blue sky... that may be your issue. Now if you had a Google Nexus S 4g or some other phone with a crappy internal antenna, I would probably say blame the phone. However, the Photon has that good Motorola build quality and the reception is superb on this beast. I get such great reception, even in places that I notoriously had low reception.
Last example: At my parents house, my Samsung Instinct -3 years ago- had 1 bar of reception, my Palm Pre had 1-2 bars reception, my short lived Google Nexus S 4g wouldn't really get a connection it would just say waiting for coverage. My Photon gets 3 bars consistent throughout the house and 3g holds steady the whole time.
I hope my story helps. :-\