rpm install from rescue CD



I'm trying to use rpm from the 1st install CD of FC4. I'm trying to
re-install glibc packages that didn't get installed properly leaving the
system without ld. I've tried the following:

rpm -U --replacepkgs --root /mnt/sysimage glibc*

and am getting

error: can't create transaction lock on /var/lib/rpm/_db.000

What can be done?

Bob T.
.