Yes it is likely the breaker on the generator itself. It is a common issue. Usually looks like a toggle switch.
Also, many RVs do not have an automatic transfer switch and you switch power sources (ie. Generator vs home outlet) by physically plugging in your RV power cord to either the generator outlet (usually in the same compartment as the cord itself) or another power source (ie. a home outlet, or the campsite power stand). When running your RV off the generator, that cord must be plugged into the generator outlet.
Hope that helps.
Chris