Upload rejected

[Sascha Manns <Sascha.Manns@mailbox.org>]

Hello list,

today i tried to upload a package to mentors, but sadly it was
rejected:

Your upload does not contain a valid signature. Output was:

gpg: Signature made So 17 Dez 2017 08:27:40 UTC using RSA key ID
3EF12E85
gpg: Can't check signature: public key not found

Before uploading i added that mentioned key:

gpg --keyserver keyring.debian.org --send-keys
3F25F4D2A4F30A9DBAE2191DC70ECCE03EF12E85
gpg: sending key C70ECCE03EF12E85 to hkp://keyring.debian.org

dput says by uploading:

LANG=C dput mentors ignore-me_0.1.2-1_amd64.changes
Checking signature on .changes
gpg: Signature made Sun Dec 17 09:27:40 2017 CET
gpg:                using RSA key C70ECCE03EF12E85
gpg: Good signature from "Sascha Manns <Sascha.Manns@mailbox.org>"
[ultimate]
Good signature on /home/sascha/pbuilder/ignore-me_0.1.2-
1_amd64.changes.
Checking signature on .dsc
gpg: Signature made Sun Dec 17 09:27:07 2017 CET
gpg:                using RSA key C70ECCE03EF12E85
gpg: Good signature from "Sascha Manns <Sascha.Manns@mailbox.org>"
[ultimate]
Good signature on /home/sascha/pbuilder/ignore-me_0.1.2-1.dsc.
Uploading to mentors (via http to mentors.debian.net):
  Uploading ignore-me_0.1.2-1.dsc: done.
  Uploading ignore-me_0.1.2.orig.tar.xz: done.    
  Uploading ignore-me_0.1.2-1.debian.tar.xz: done.
  Uploading ignore-me_0.1.2-1_all.deb: done.  
  Uploading ignore-me_0.1.2-1_amd64.buildinfo: done.
  Uploading ignore-me_0.1.2-1_amd64.changes: done.
Successfully uploaded packages.

But why the upload fails?

Greetings
Sascha
-- 
Sascha Manns
Email: Sascha.Manns@mailbox.org | Blog: http://saigkill.tuxfamily.org
GPG: 0x168428cdb1f20ab1