EngiBOX Installation on 582 UL

I have installed AvMap's EngiBOX on my 582. However, the EGT and CHT readings are too low, e.g. -150C at room temperature, or often show the X mark for a faulty connection.

I first checked that there were no faults in the fuselage wiring and that everything was conducting.
I had also selected the correct TC for the EngiBOX sensor setting and used the correct thermocouple wiring.

As there is still an abnormal value, I decided to test the EngiBOX by remove it from the aircraft and connected it to a 12V power source on my desk.
I prepared a type K thermocouple, which I use to measure temperature during normal maintenance (to make sure the sensor is not bad enough).
When I connect it to the EGT+/- on the EngiBOX, it still shows an abnormal value that is too low. When I heat it up with a lighter to test it, the temperature rises, but it is still not a normal value.

The connection at the moment is as follows;
POWER+ : 12V+ of the power supply on the desk
POWER- : GND of the power supply on the desk
TEMP1+ : + of the K-type thermocouple
TEMP1- : - of the K-type thermocouple

If you have the same experience or a solution, please let me know.