Map version diffrent from server

[excaliber]

If i go out onto the net and join a server with a map i dont have it will work fine. But when I create my own server and play with my friends the maps that they download from me always come up with that error message. I am not uploading maps and all associated files to a webhosting service, so I am guessing they are downloading striaght from my pc when connectng to my server.

Please help

Thanks in advance