Username not working when adding to PT

[Davsto]

To be specific, the user +__+. When I enter his name into the box for adding users to the private topic and click "Add User", it says "invalid username", not adding it to the PT. A fix for this would be appreciated.

Edit: apparently the user tag doesn't work either - http://forum.mafiascum.net/memberlist.p ... le&u=28520