Camera trigger doesn't work due to low signal output

Hello!
I’m having trouble with the camera trigger function.

I’m using a pixhawk cube orange for a VTOL drone. Servo1-10 are assigned to Aileron, Elevator, Throttle, Rudder and Motor. As Servo11-14 are free, one of them is assigned as camera trigger.
Test flight was OK. But only the camera trigger is not working.

The parameters related to the camera trigger are set to as follows.
CAM_SERVO_OFF 1100 PWM
CAM_SERVO_ON 1900 PWM
CAM_TRIGG_TYPE 0: Servo
SERVO11_Function 10: Camera trigger

However, nothing happens when I do a camera trigger on the mission planner screen.
So I checked the condition of the servo rail, AUXOUT 3-6 (Servo 11-14) have output voltage of 5.27V.
The voltage of signal pins were as follows.
AUXOUT_3: 0.22V (Camera trigger)
AUXOUT_4: 0.02V (disabled)
AUXOUT_5: 3.30V (disabled; I don’t know why. broken?)
AUXOUT_6: 0.02V (disabled)

If I push a camera trigger button on the mission planner screen, the signal pin of AUXOUT_3 responds, but the voltage only rises to 0.31V. I remember that the signal pin voltage rose to about 3.3V when the camera trigger was successful in the past. I don’t understand why the camera trigger is no longer working. Could anyone give me some advice where is the problem?

Best regards,
Tatsuya