GFCI at shore power tripping

Found my multi meter. There is no continuity between the pins on the shore power cord (disconnected from house and adapter removed) as well as I tested the adapter and there is no continuity there either. That being said, I just discovered that the extension cord from shore power is a 14 gauge extension cord. From my knowledge, I should be using a 12 or 10 gauge. Don't know if that is the issue but it needs to be corrected anyway. I am going to get a new cord and dog bone style adapter and then continue trying to isolate. If I am unable to pinpoint the issue at that point, I am going to take it in for servicing. I will keep you posted. Thanks for everyone's help!