KF Help With Dedicated Server

Hi everyone maybe some of you knows how to fix a problem?

Well i created Dedicated Killing Floor Server for now everything was ok untill i tried to enter my server but when im trying to enter it shows me this "

:Steam error an unknown steam error is preverting you to enter this server

Thats all

PLEAS I NEED HELP :confused::confused::confused::confused::confused: :(:(:(