[CentOS] Command not running in crontab

Hi,

Can anoyone tell me why this command is not executed (or it is without 
success) from crontab, but works perfectly from the command line ?
(yes, i've restarted crontab service)


# clean up postmaster
00 30 * * * root /usr/bin/find 
/var/qmail/maildirs/postmaster at telbit.pt/Maildir/new -type f -print0 | 
xargs -0 -n 50 rm


The mind boggles...

Any help would be appreciated.

Warm Regards,
Mário Gamito