Why cannot I upload my package?

[Tomohiro KUBOTA <kubota@surfchem0.riken.go.jp>]

Hi,

I am a new maintainer registered on 19th August.
I cannot upload my package using dupload --to master.

Immediately after I found I was registered as an official
developer, I registered my GPG key using 

  gpg --keyserver keyring.debian.org --send-keys "kubota"

and wait for about two days so that the key appears in
http://db.debian.org/ pages.  Then I uploaded my package
(whose previous version is already in Debian by sponsorship).

Then I got a mail like that:

> PGP/GnuPG signature check failed on language-env_0.08_i386.changes
> (Exit status 0)
> language-env_0.08_i386.changes has bad PGP/GnuPG signature!
> Removing language-env_0.08_i386.changes, but keeping its associated files for now.
> 
> Greetings,
> 
> 	Your Debian queue daemon

However, gpg --verify says that the file is properly signed, of course.
Did I do someting wrong?

---
Tomohiro KUBOTA <kubota@debian.org>
http://surfchem0.riken.go.jp/~kubota/