tau_angle output shows nan value.(attitude controller with joystick input for x type quadrotor vehicle using embedded coder support package for px4 autopilot)

Hi, I'm studying the embedded coder with the embedded coder support packages for px4 autopilot.

I want to know the values of controlled tau_angles(tau_yaw, tau_pitch and tau_roll), so I added a display block to one of the outputs.

When I connected to PX4 host target, the output indicated a single value, however, when I connected to my pixhawk1, the output indicated a nan value.

I checked all values before pid controller and all of them have their values in normal.

I don't know why does the output have a nan value.