Autotakeoff problem with airspeed

Hello all,
I´ve done hundreds of autotake off with the x5 planes without airspeed. The other day, I decided to install the Measurement Specialties 4525DO. I always do a preflight calibration, but when I launch it with the catapult the aircraft decrease the throttle and cannot climb.
I´m using Pixfalcon, quth arduplane 4.0.5 and using the autotakeoff with waypoints, no mode. I always use 20 of pitch angle, a and altitude of 70m.
you know what could be happening?