Error with encrypting: unusable public key

[Olaf Gellert]

Hi all,

I keep getting an error trying to encrypt to the key
0xCC21E10F. The key is self-signed, gpg --check-sigs
does not complain, but still when I try to encrypt
I get:

gpg: 0xCC21E10F: skipped: unusable public key

I am using gpg 1.4.5 on a Linux box (SuSE 10.2).
Could this be a matter of algorithms? The key is
available on the keyservers. Thanks for help,

Olaf

-- 

Dipl.Inform. Olaf Gellert                   INTRUSION-LAB.NET
Senior Researcher,                      www.intrusion-lab.net
PKI - and IDS - Services        olaf.gellert at intrusion-lab.net