So the generator runs but you detect no power at the breaker panel (presumably using a voltmeter?). Is this a new problem (it has worked in the past) or your first time trying it out? And you are sure your coach has a transfer switch and does not require you to plug the shore cord into a generator outlet?
Sorry to ask for such basic clarifications, but these are common reasons when RV owners say their generator isn't providing power.
To find the ATS you may have to trace the shore cord or generator wires until they join at the ATS. If you can easily get at the area just behind the breaker panel, it's worthwhile to look there first because its a fairly common location.