centos and Fedora dual boot issue - Updated grub2

After installing both CENTOS  and Fedora 18, Centos  "disappeared" from Grub menu. Only Fedora 18 is bootable.

Then, able to restore Centos by issuing following commands.

#grub2-mkconfig -o /boot/grub2/grub.cfg

#grub2-install /dev/sda