GnuPG, KDE and Crytop plugins

[Chris]

I'm using KDE with gnupg for the encrytion tool. When a message come in that 
is signed, I get this in the email:

Message was signed with unknown key.
The validity of the signature cannot be verified.
Problem: OpenPGP plug-in was not specified.
Use the 'Settings->Configure KMail->Security' dialog to specify the plug-in or 
ask your system administrator to do that for you.

I guess what I'm asking, is what else is needed for this?
I'm assuming I'm missing this "crypto plugin". Can someone point me in a 
direction or a site with a how-to?

-- 
Best regards,
Chris