If you jumper at the distribution panel then if you plug into 50 amps at a campground bad things WILL happen (Very bad, direct short on 240 volts, Major sparks)
Now you said you made up a cord with the Twist Lock on one end, and an Outlet on the other., I assume this is a 50 amp outlet on the other end.. YES?NO? If YES read on
The 50 amp outlet has 4 wires/screws/contacts
One screw is Green, or marked "G", the assoicated pin is kind of round
This is the safety ground, may be not connected at the generator end
one is Silverish or marked W.. This is the WHite wire
The other two screws are copper colored may be marked with a greek letter and a number or L-1/L-2 or two greek letters. The BLACK wire goes to BOTH of these.
Your problem is that you have connected the safety ground, which is likely N/C (not connected) at the generator, to one of the legs. on the outlet I am guessing.
There are diagrams on NOShockZone if you need them.