Fedora – Meaning of the yum error “Package tuple (…) could not be found in rpmdb”

I just want to install two packages in my Fedora 15 but I am getting some weird
error.

Command:
yum install @development-tools

Error:

Loaded plugins: langpacks, presto, refresh-packagekit Setting up
Install Process Package flex-2.5.35-13.fc15.x86_64 already installed
and latest version Error: Package tuple ('gcc', 'x86_64', '0',
'4.6.0', '6.fc15') could not be found in rpmdb

Command:
yum install fedora-packager

Error:

Loaded plugins: langpacks, presto, refresh-packagekit Setting up
Install Process Error: Package tuple ('fedora-packager', 'noarch',
'0', '0.5.9.0', '1.fc15') could not be found in rpmdb

On first command it says package already installed and latest version but why I got that error line.How to fix this errors?