repo-send will fail to create the database if the repository has a none existent database. For example. if testing has been merged and cleaned and is fresh with no files, adding packages will fail.
---: Found no repo database for repository linux-testing at:
linux-testing/os/i686/linux-testing.db.tar.gz
---: Found no repo database for repository linux-testing at:
linux-testing/os/x86_64/linux-testing.db.tar.gz