try this:
from
http://kontact.kde.org/kmail/kmail-pgpmime-howto.php#gnupg
Before using gpg, you need to start gpg-agent:
eval "$(gpg-agent --daemon)"
--cut--
Starting with KDE-3.3 you can add the gpg-agent command in ~/.kde/env/gpgagent.sh (the filename doesn't matter). The contents of ~/.kde/env/ is sourced by startkde.
so look at your ~/.kde/env dir (or create it if there isn't) for gpgagent.sh and add:
eval "$(gpg-agent --daemon)"
to it. If you don't have a gpgagent.sh in ~/.kde/env create it and make it readable and executable.
hope it helps...