NRPE: Unable to read output

I download you plugin to test it but it didn’t work for me and give me this error

Remote host:
I run command
./check_mailstat.pl -w 5:0:0:0:0:0 -c 10:0:0:0:0:0
OK: sent:0.03 received:0.03 bounced:0.00 rejected:0.00 virus:0.03 spam:0.00 |sent=0.03 received=0.03 bounced=0.00 rejected=0.00 virus=0.03 spam=0.00

/etc/init.d/nrpe.cfg
command[check_mailstat]=/usr/lib/nagios/plugins/check_mailstat.pl -w $ARG1$ -c $ARG2$

On server Nagios

./check_nrpe -H remotehost -c check_mailstat -a 50:0:0:0:0:0

NRPE: Unable to read output

How to configure and fix?