ssh: Failure reading data from SSH server

[misch]

Hi,

I set up a simple ssh check on my zabbix 1.8.5. Zabbix sets this item to unsupported and the log tells me: Failure reading data from SSH server.

Definition of the item:

<item type="13" key="ssh.run[check_ping, , , ]" value_type="0">
<description>check_ping</description>
<ipmi_sensor></ipmi_sensor>
<delay>30</delay>
<history>90</history>
<trends>365</trends>
<status>3</status>
<data_type>0</data_type>
<units>s</units>
<multiplier>0</multiplier>
<delta>0</delta>
<formula>0</formula>
<lastlogsize>0</lastlogsize>
<logtimefmt></logtimefmt>
<delay_flex></delay_flex>
<authtype>0</authtype>
<username>username</username>
<password>password</password>
<publickey></publickey>
<privatekey></privatekey>
<params>/home/username/check_ping.sh 10.255.0.43</params>
<trapper_hosts></trapper_hosts>
<snmp_community></snmp_community>
<snmp_oid></snmp_oid>
<snmp_port>161</snmp_port>
<snmpv3_securityname></snmpv3_securityname>
<snmpv3_securitylevel>0</snmpv3_securitylevel>
<snmpv3_authpassphrase></snmpv3_authpassphrase>
<snmpv3_privpassphrase></snmpv3_privpassphrase>
<valuemapid>0</valuemapid>
<applications/>
</item>

I see SSH traffic on the line and running the command form the command line also works:
# sudo -u zabbix username@host /home/username/check_ping.sh 10.255.0.43; echo $?
.234
0

Thanks for any help.

Greetings,

Michael.