it ses joining game for them, but then it won't join? why isn't it working? or possible reasons i could look at?

Check this link.

Are you sure they have the right port typed in for your server? No passwords, firewall issues, etc...check the link and then search. At least look through the Soldat Bugs forum and other areas, because this topic has been addressed multiple times, even recently.

make sure you didn't ban them :P

lol ... that would be retarded

(moved from Gen. Disc. to Server Corps)

Please have a look at this topic:
Read Me Second - Running A Soldat Server [2]