Greetings All

Okay, i'm in serious need of help regarding a galaxy forge map I made. I have tested the map and it works fine, i sent it to two of my mate and they set it up fine. We went to play and whenever they tried to join my game they kept getting the message " you dont have the right files to play this game ". So one of them set it up, the other could join but when I tried i got the same message.

I'v replaced my file with the one I sent them to confirm it is the same file but alas, the same message.

Anyone know whats going on please?