cpu temp displayed but graph blank

[thindata]

On a vanilla debian machine the cpu temperature is displayed and updated but the graph is always blank?

[netzien]

I run dash on a odroid-m1 arm server ,run ubuntu 22.04.
I edit .../server/linux_json_api.sh
cpu_temp() {
...
"raspbian")
cpu=$(</sys/class/thermal/thermal_zone0/temp)
echo "$((cpu/1000))" | _parseAndPrint
...
...
"ubuntu")
cpu=$(</sys/class/thermal/thermal_zone0/temp)
echo "$((cpu/1000))" | _parseAndPrint
...

and now works