grub doesn't detect partition

["Ксения Шкарупа" <ksenks gmail com>]

Hello,

I need install Cent OS on /dev/sda3.
After install all selected packages Anaconda report "Installing bootloader..."
and give booty try to do following:

root (hd0,2)
install  /grub/stage1 d (hd0,2) /grub/stage2 p (hd0,2)/grub/grub.conf

these command are failed with error from grub "No such partition".
In this moment grub can detect only (hd0,0), but if reboot system grub will detect all partition.

Why grub can't detect all partition in the end of installation?

Best regards,
Kseny