> gpg: skipped "Mauro Lizaur <lavaramano@gmail.com>": secret key not available
> gpg: [stdin]: clearsign failed: secret key not available
> ...
> pkg-buildpackage: warning: Failed to sign .dsc and .changes file"

Most probably you didn't include this exact uid in your secret key. You
can list you uids with a simple call of "gpg -K" and check if "Mauro
Lizaur <lavaramano@gmail.com>" is listed there.

If not, you can add this uid by invoking gpg with --edit-key and use the
command adduid at the interactive prompt.