error #22 invalid engine

[bk]

Whenever I try to sign an e-mail in KMail (KDE 3.1.2, SuSE 8.2) I get an error 
from gpgme-smime.so that it cannot find a valid engine (error #22).

Note: I didn't install a key pair + certificate yet, so maybe this is the 
cause but I find it kind of strange that the plugin first warns me that I 
don't have the right certificate, then allows me to click "use certificate" 
and then complains about a missing engine. If this is caused by the fact that 
I have NO certificate at all then the behavious is, to say the least, 
confusing and inconsistent to the end user.

Or is there another reason for this error 22?