[Dovecot] statfs() error message

i use openbsd/i386, dovecot-1.0b7

i see the error message in maillog dovecot: statfs(mail/username) failed: No such file or directory

i guess the statfs() can not find the directory, because i run dovecot-imap in chroot

userdb static { args = uid=34567 gid=34567 home=/var/./mail }

i am sure, i have this directory "/var/mail/username", and i add "nfs_check = no" to dovecot.conf, the error message will gone