Problem with ADC readings on Pixhawk


I’m working with a pixhawk, and I am not getting any readings in any of the adc imput pins (13, 14 and 15) where I have connected an analog sensor.
I tried running the AnalogIn example, and I get all 0. I don’t think the sensor is the problem, since I tried reading it’s output in another board (an arduino) and it works just fine.

Any ideas? What am I doing wrong?

Thanks in advance!