Call of duty 4 erorr

When ever i start a call of duty private server i always get this error:
does anyone know whats rong with it and how i can sort it out
thanks
Answer #1
Punkbuster has to be installed perhaps?
Answer #2
Update your punk buster and while playing MP… enable it in the options!
Answer #3
i have installed it and as soon as i start a multiplayer game it kicks me out nd that appens
nd its already enabled btw punkbuster is updated
Answer #4
http://www.twistedgamingservice.com/forums/Punk-Buster-FAQ-f114/Service-Communication-Failure-Handshaking-Failed-t3152.html
Answer #5
thanks ima try that out