RV refrigerators can be tricky at times. If your RV has been sitting for a while without use, spiders and other bugs can make nice little homes in the backs of your appliances, creating a blockage with debris or spider webs at the burner or on the sparker.
1. Make sure the propane is off.
Possible solution... take an air hose and blow the back of your refrigerator out or simply blow on it yourself. Be sure to look at the burner and sparker to see if they are dirty or corroded, and give it a good cleaning.
Turn the propane back on and try to light it again