Gnus decrypt mail works with openssl but fails with epg

[Klaus Zeitler <klaus.zeitler@nokia.com>]

Hello,
I have an odd problem with encryption. I send myself a signed and
encrypted email with something like:
 openssl smime -sign -in test.txt -signer CertAndKey.pem -text | openssl smime -encrypt -from klaus.zeitler@alcatel-lucent.com -to klaus.zeitler@alcatel-lucent.com -subject "Signed and Encrypted message" CertAndKey.pem | sendmail klaus.zeitler@alcatel-lucent.com

I can decrypt/verify/read this mail with Gnus only when I use
 (setq mml-smime-use 'openssl)
but not with
 (setq mml-smime-use 'epg)
There I see in the EPG debug buffer:
--- snip ---
GPG_AGENT_INFO=/tmp/gpg-0A12Kv/S.gpg-agent:5003:1
/usr/bin/gpgsm --no-tty --status-fd 1 --yes --output /tmp/epg-output1248i8M --decrypt -- /tmp/epg-input1248VyG
[GNUPG:] ERROR decrypt.algorithm 50331732 1.2.840.113549.3.2
[GNUPG:] DECRYPTION_FAILED
--- snip ---

BTW I can also read this email with Thunderbird.


When I send myself a signed+encrypted email from Thunderbird, I see in
the EPG debug buffer:
--- snip ---
GPG_AGENT_INFO=/tmp/gpg-0A12Kv/S.gpg-agent:5003:1
/usr/bin/gpgsm --no-tty --status-fd 1 --yes --output /tmp/epg-output1248JUr --decrypt -- /tmp/epg-input12488Jl
[GNUPG:] ENC_TO FFFFFFFFE1EA1359 0 0
[GNUPG:] DECRYPTION_OKAY
--- snip ---


So it seems as if there's something wrong with my settings for EPG,
but I have no idea what. I only have these 4 lines in my init file
for EPG usage:
 (require 'epa-file)
 (epa-file-enable)
 (setq epg-debug t)
 (setq mml-smime-use 'epg)


Maybe the error above:
[GNUPG:] ERROR decrypt.algorithm 50331732 1.2.840.113549.3.2
gives a hint to what's wrong in my setup. 


Klaus