Problem on uploading AHRS_test.pde on the APM

I attached Ultrasonic Sensor and gimbal servo on my S550 Copter.

the servo will fix sensor’s direction when drone tilt forward when it is flying.

So I must get drone’s AHRS Data(Pitch Angle)

So I uploaded AHRS_test.pde to APM board.

I successfully uploaded and tested several example sketch file on the APM Board

but this time I met error.

I never touched one line of source code of the example sketchs but It genereated error.

error message says

"
class_ap_inertialsensor_MPU6000 has no member named ‘init’

class_ap_inertialsensor_MPU6000 has no member named ‘init_accel’
"

I’m stuck in this error message along the day and still dont have a clue.

I searched google and forums but it is hard to find the solution…