"Can't check signature: public key not found" after package upload

[Damien Lecan <dev@dlecan.com>]

Hello,

For severals weeks (~begin of April), I'm not able to upload new
packages anymore.

Each time, I get :

  Unfortunately your package "freefilesync" was rejected because of
the following
  reason:
  Your upload does not contain a valid signature. Output was:
  gpg: ... using RSA key ID 33A7B658
  gpg: Can't check signature: public key not found

But I succeed in uploading many versions of my package before (see
http://mentors.debian.net/package/freefilesync).
And this key still works for my Ubuntu PPA uploads.

I tried to setup a new GPG key, with the same result : public key not found

What can I do to be able to submit new packages ?
Thanks

Damien