Empty logfile (I think logrotate problem)

[ergos]

Hi all,
I noticed that in /var/log each relevant log file is empty (0 byte).

I tryed to reboot and then they started to populate but when they were processed and become .1 .2 .3 etc... the main one (the one yet to be processed) becomed empty again...

Any idea?

Plesk8,1, CentOS, Virtuozzo

Thanks a lot,
Filippo