Problems decrypting a mail with my openpgp card

[Michael Bienia]

Hello,

I've received an encrypted mail which I now have problems to decrypt it
with my key on a openpgp card. The mail was encrypted for two recipients
but I assume this has nothing to do with my problem.

The output is (stripped the output about the second recipient):
,----
| $ gpg --use-agent --verbose --decrypt test-mail
| gpg: armor header: Version: PGPfreeware 6.5.3 for non-commercial use <http://www.pgp.com>
| gpg: public key is 0DCB0431
| gpg: public key is 02CC2588
| gpg: using subkey 02CC2588 instead of primary key 968BD587
| gpg: sending command `SCD PKDECRYPT' to agent failed: ec=6.18
| gpg: using subkey 02CC2588 instead of primary key 968BD587
| gpg: encrypted with 1024-bit RSA key, ID 02CC2588, created 2006-03-13
|       "Michael Bienia <michael at vorlon.ping.de>"
| gpg: public key decryption failed: general error
`----
Doit the same without gnupg-agent (again without the output for the
second recipient):
,----
| $ gpg --no-use-agent --verbose --decrypt test-mail
| gpg: armor header: Version: PGPfreeware 6.5.3 for non-commercial use <http://www.pgp.com>
| gpg: public key is 0DCB0431
| gpg: public key is 02CC2588
| gpg: using subkey 02CC2588 instead of primary key 968BD587
| gpg: detected reader `SCM SPR 532 00 00'
| gpg: reader slot 0: active protocol: T1
| gpg: slot 0: ATR=3B FA 13 00 FF 81 31 80 45 00 31 C1 73 C0 01 00 00 90 00 B1
| gpg: AID: D2 76 00 01 24 01 01 01 00 01 00 00 08 55 00 00
| gpg: using subkey 02CC2588 instead of primary key 968BD587
| gpg: encrypted with 1024-bit RSA key, ID 02CC2588, created 2006-03-13
|       "Michael Bienia <michael at vorlon.ping.de>"
| gpg: public key decryption failed: wrong secret key used
`----
gpg --card-status lists the subkey 02CC2588 as my authentication key. I
created the keys in the order recommended by the subkey_howto on
www.fsfe.org: auth, sign, encrypt.

How get I this mail decrypted?

Thanks,
Michael