After applying some kernel patches and rebooting, I noticed /etc/init.d/purge-kernels fails on boot on all of my SLES 11 SP2 servers. When I try firing the main /sbin/purge-kernels command, I get the following:

$ sudo purge-kernels
/sbin/purge-kernels: multiversion.kernels not configured in /etc/zypp/zypp.conf, exiting.

$ cat /etc/zypp/zypp.conf | grep multi
#multiversion = provides:multiversion(kernel)
I tried uncommenting multiversion in zypp.conf, but no change in the purge-kernels output. Any idea? I'd like to get rid of some of the old kernels on my system as they are taking up disk space, and I figured this purge-kernels was probably the cleanest approach. Is there another way to safely delete the old kernels off my system?