Graph not generated for a service check_by_ssh

Hi, one on my server runs and homemade application. I need to monitor the active sessions with this application. I can do that adding a service by_ssh which runs a script on the remote server which returns the number. It works fine except for the graph. No graph are generated.
Can anyone point me in the right direction?

[email protected]:~$ /opt/librenms/check-services.php -d -h 4
Starting service polling run:

SQL[SELECT D.,S.,attrib_value FROM devices AS D INNER JOIN services AS S ON S.device_id = D.device_id AND D.disabled = 0 AND S.device_id = ? LEFT JOIN devices_attribs as A ON D.device_id = A.device_id AND A.attrib_type = “override_icmp_disable” ORDER by D.device_id DESC; [4] 1.57ms]

Nagios Service - 5
Request: ‘/usr/lib/nagios/plugins/check_by_ssh’ ‘-H’ ‘’ ‘-4’ ‘-C’ ‘/usr/bin/sh /home/cust/’ ‘-l’ ‘cust’ ‘-E’
Perf Data - None.
Response: 39
SQL[UPDATE services set service_message=? WHERE service_id=? [“39”,5] 0.62ms]

/opt/librenms/check-services.php 2022-05-23 09:46:44 - 1 services polled in 0.622 secs