run-all-webalizer.pl from logrotate

Hi, I tried to run run-all-webalizer.pl as prerotate script from /etc/logrotate.d/apache2, but I get these errors:

[code:1] Undefined subroutine &virtual_server::has_ftp_chroot called at ./virtual-server-lib.pl line 167. Compilation failed in require at /usr/share/webmin/virtual-server/run-all-webalizer.pl line 24. error: error running shared prerotate script for /var/log/apache2/.log /var/log/apache2/_log [/code:1]

In /etc/logrotate.d/apache2 I added these lines:

[code:1] prerotate /usr/sbin/virtualmin run-all-webalizer.pl endscript [/code:1]

If I run "virtualmin run-all-webalizer.pl" from a terminal as root works perfectly.

Thanks in advance for any tip to fix it. Santi