[exim] Exim4 & QueryProgram

Hi all,
I have created in my exim4.conf.template a new router with this
characteristics:
maildir_overquota2:
driver = queryprogram
command = /usr/local/sbin/checkQuota $local_part $domain
command_user = mail
command_group = mail

This is my script (/usr/local/sbin/checkQuota)
#!/bin/bash
echo PASS

When I test exim with:
exim4 -oMr spam-scanned -d -bt root@???
is ok!

But when I try with:
exim4 -bh IP I have this error:

calling maildir_overquota2 router
>>> maildir_overquota2 router: defer for root@???
>>> message: maildir_overquota2 router: command returned non-zero
code 127
>>> ----------- end verify ------------
>>> accept: condition test deferred
451 Temporary local problem - please try later
LOG: H=localhost () [127.0.0.1] F=<user1@???> temporarily rejected
RCPT root@???: maildir_overquota2 router: command returned
non-zero code 127

Could you help me?

Thanks
Marco