New battery, no interior lights

Maybe.  Double check to make sure your connections at the battery are 'tight.'  I once hand tightened the nuts on the battery, went inside, and had nothing.  Went back out and got a wrench, turned maybe 1/2 turn and lights worked. 

Do lights work when you are hooked up to 120 shore power?  When was the last time the lights worked and what power source were you using?  Have you checked your fuses on the 12v side.  Very easy to short out the 40 amp fuses if you momentarily short out a wrench on the metal frame while snugging down.  More info please.