Problems uploading package to Launchpad due to "checksum mismatch" error

I'm having a lot of problems uploading my showdown project to a PPA.

I've setup correctly PGP keys and my public SSH key to Launchpad. I've packaged with debuild my C++ project, producing a source package lintian gave me only those two warnings that I think are ok for the showdown rules:

W: massren source: native-package-with-dash-versionW: massren source: binary-nmu-debian-revision-in-source 1.0-0extras12.04.1~ppa2

Producing a binary package works too, and the package installs without problem on my Ubuntu 12.04 "Precise" machine. I only have a few more lintian warnings about the fact I'm installing files into /opt/extras.ubuntu.com/<packagename>.

I'm uploading with the command:

dput ppa:gabrielegreco/massren massren_1.0-0extras12.04.1~ppa2_source.changes

When I upload with dput I have no errors, signatures seems ok, and public key seems to be accepted, too (since the upload goes on without asking for passwords…). This is the output from dput:

$ dput ppa:gabrielegreco/massren massren_1.0-0extras12.04.1~ppa2_source.changes  Checking signature on .changes  gpg: Signature made Mon 02 Jul 2012 10:00:38 AM CEST using RSA key ID 49982576  gpg: Good signature from "Gabriele Greco <gabrielegreco@gmail.com>"  Good signature on /home/gabry/no-backup/massren_1.0-0extras12.04.1~ppa2_source.changes.  Checking signature on .dsc  gpg: Signature made Mon 02 Jul 2012 10:00:33 AM CEST using RSA key ID 49982576  gpg: Good signature from "Gabriele Greco <gabrielegreco@gmail.com>"  Good signature on /home/gabry/no-backup/massren_1.0-0extras12.04.1~ppa2.dsc.  Uploading to ppa (via ftp to ppa.launchpad.net):  Uploading massren_1.0-0extras12.04.1~ppa2.dsc: done.  Uploading massren_1.0-0extras12.04.1~ppa2.tar.gz: done.      Uploading massren_1.0-0extras12.04.1~ppa2_source.changes: done.  Successfully uploaded packages.

At the moment I'm not receiving responses from Launchpad site, but the upload does not show in the PPA page.

Previous attempts gave me response emails with different kind of errors:

File massren_1.0-0extras12.04.1~ppa1.tar.gz mentioned in the changes has a checksum  mismatch. 1503fa155226cbc4aba2f8ba9aa11a75 != 294a5e0caf3fe95b0b007a10766e9672File massren_1.0-0extras12.04.1~ppa1.tar.gz mentioned in the changes has a checksum  mismatch. 1503fa155226cbc4aba2f8ba9aa11a75 != 294a5e0caf3fe95b0b007a10766e9672

Or more cryptically:

GPG verification of  /srv/launchpad.net/ppa-queue/incoming/upload-ftp-20120629-163320-001135/~gabrielegreco/massren/ubuntu/massren_1.0-0extras12.04.1~ppa1.dsc  failed: Verification failed 3 times:    ["(7, 58, u'No data')", "(7, 58, u'No data')", "(7, 58, u'No data')"]Further error processing not possible because of a critical previous error.

Any idea how can I solve this problem? I'm new to Ubuntu packaging, so I may miss some step… Is there is an alternative to dput (a/k/a manual upload)?