3 things to check without specific information on your genset.
1) The genset itself probably has breakers on it. Make sure they are on. If they are off, you will get no power.
2) Most RVs have a 30 or 50 amp receptacle that is the power output of the generator. Your shore power cord will plug into that, or be plugged into shore power. This way you can't be plugged into both at the same time - the plug only goes into one source - shore or the generator. Make sure your shore power cable is plugged into the generator outlet.
Unless...your RV has an auto switchover between shore power and generator.
3) Check the breakers at the power distribution panel inside the RV.