You have almost answered your own question.
If power wasn't getting to the breaker, then either the breaker in the post is bad (you said you checked it) or you shore power cable is bad somewhere along the line. Did you check your end of the shore power cable? (It sounds like you have a surface mount male and an extension cord.) If the extension cable is a made-up and not a molded plug, disassemble it and you will probably find the problem. If that doesn't get it, then that surface mount male is where it is....
Good Luck
Matt