ppa - 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-version
W: massren source: binary-nmu-debian-revision-in-source 1.0-0extras12.04.1~ppa2

Producing a binary package works to and the package installs without problem on my ubuntu 12.04 machine, I only have a few more lintian warnings about the fact I'm installing in /opt/extras.ubuntu.com/

I'm uploading with:

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 accepted to (since the upload goes on without asking passwords...):

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 "
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 "
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 e-mails with different kind of errors:

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

Or more cryptic:

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...

There is an alternative to dput (aka manual upload)?