Help with Electric hookup cable

Just purchased a Harmony Autosleeper 1999.  We just tried to plug in the electric hook up to the van but the cover on the plug is preventing us pushing it in all the way.  Total novice so not sure if we are doing something wrong.  Any help appreciated

We have opened the cover as far as it will go but it gets caught on the side of the van so we cant get it to go in all the way and cant see any way without breaking the cover off???

No the opposite actually the cover is stopping us pushing it in all the way it gets stuck on the side of the van

We lift up the cover on the van then try to push the plug in after lifting the blue protective cover on the plug but it will only go in so far before the blue cover on the plug gets stuck on the outside of the van.  Does that make more sense?

I suspect that they are opening the cover on the plug (on the EHU cable) too far - trying to fold it right back through 180 degrees - when actually it should only open through 90 degrees and the protruding cover slides inside the socket on the van (as already said in the first reply).

Yes yes yes!!!  We have lift off thankyou so much for your help guys