[Dovecot] how to talk with doveadmin unix socket

[Piotr Rotter]

Hello,

I would like to get mailbox quota by doveadm unix socket 
(/var/run/dovecor/doveadm-server). I get from strace syntax of comunication:

write(9, 
"VERSION\t1\t0\nUSER\t1\tpiotr.rotter at active24.pl\tservice=doveadm\n", 
60) = 60
read(9, "VERSION\t1\t1\nSPID\t20805\n", 8192) = 23
read(9, 
"USER\t1\tpiotr.rotter at active24.pl\temail=piotr.rotter at active24.pl\tclear=7T33z456\thome=/vm/08/A/active24.pl/piotr.rotter/\tuid=502\tgid=502\tquota_rule=*:storage=2097152000B\tquota_rule2=*:messages=50000\n", 
8169) = 196

and I wrote super simple client in php:

<?php
$sock = stream_socket_client('unix:///var/run/dovecot/doveadm-server', 
$errno, $errstr);
fwrite($sock, 
"VERSION\t1\t0\nUSER\t1\tpiotr.rotter at active24.pl\tservice=doveadm\n");
echo fread($sock, 4096)."\n";
echo fread($sock, 4096)."\n";
fclose($sock);
?>

But i get only "+" sign and line in errorlog as below:

2013-02-28T00:39:56.377437+01:00 kurier9 dovecot: doveadm: Error: 
doveadm client not compatible with this server (mixed old and new binaries?)

I would be very grateful for your help with this problem, what I doing 
wrong.

My current dovecot version is 2.1.13