Welcome to the forum!
Where to begin? Sounds like the thermocouple isn't working properly. You can try cleaning the thermocouple bulb with some scotch-brite or fine sandpaper. Make sure the flame is enveloping the bulb when lit and the refrigerator is level.
Try a search for keywords: refrigerator, thermocouple, level, etc. There have been many threads about gas fridges recently with tons of good information that will help you. I certainly wouldn't replace the fridge without some exhaustive troubleshooting first and then if you still can't get it to work seek help from an RV refrigeration repair place or a dealer.
Link to a good discussion on pilot lights and thermocouples. http://www.jaycoowners.com/forums/sh...ad.php?t=19963