When I perform some yum command, happens a error, it follows:

Loading "installonlyn" plugin
Setting up Install Process
Setting up repositories
core
Cannot find a valid baseurl for repo:core
Error:Cannot find a valid baseurl for repo:core

follows my repos configuration:

file fedora-core.repo

[core]
name=Fedora Core $releasever - $basearch
#baseurl=http://download.fedora.redhat.com/pub/fedora/linux/core/$releasever/$basearch/os/
mirrorlist=http://fedora.redhat.com/download/mirrors/fedora-core-$releasever
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora file:///etc/pki/rpm-gpg/RPM-GPG-KEY

[core-debuginfo]
name=Fedora Core $releasever - $basearch - Debug
baseurl=http://download.fedora.redhat.com/pub/fedora/linux/core/$releasever/$basearch/debug/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora file:///etc/pki/rpm-gpg/RPM-GPG-KEY

[core-source]
name=Fedora Core $releasever - Source
baseurl=http://download.fedora.redhat.com/pub/fedora/linux/core/$releasever/source/SRPMS/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora file:///etc/pki/rpm-gpg/RPM-GPG-KEY

file fedora-updates.repo

[updates]
name=Fedora Core $releasever - $basearch - Updates
#baseurl=http://download.fedora.redhat.com/pub/fedora/linux/core/updates/$releasever/$basearch/
mirrorlist=http://fedora.redhat.com/download/mirrors/updates-released-fc$releasever
enabled=1
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora

[updates-debuginfo]
name=Fedora Core $releasever - $basearch - Updates - Debug
baseurl=http://download.fedora.redhat.com/pub/fedora/linux/core/updates/$releasever/$basearch/debug/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora

[updates-source]
name=Fedora Core $releasever - Updates Source
baseurl=http://download.fedora.redhat.com/pub/fedora/linux/core/updates/$releasever/SRPMS/
enabled=0
gpgcheck=1
gpgkey=file:///etc/pki/rpm-gpg/RPM-GPG-KEY-fedora

Is there some error in my repos configuration?

thanks!