Jsbsim trim fail

I met the problem that the jsbsim can’t startup because trim fail

error info below:

---- JSBSim Execution beginningOpened JSBSim control socket
… --------------------------------------------

Event 0 (start engine) executed at time: 0.000000

Start: Wednesday September 21 2016 22:06:13 (HH:MM:SS)

Trim Failed

Ground Trim
Initial Theta: 14.301766
Used gear unit 2 as aft and 0 as forward
Sorry, wdot doesn’t appear to be trimmable

Trim failed

trim computation time: 0.000200s

Trim Results:
Altitude AGL: 15.00 wdot: 3.11e+01 Tolerance: 1e-03 Failed
Pitch Angle: 0.25 qdot: -8.33e-11 Tolerance: 1e-04 Passed

Event 1 (Trim) executed at time: 0.010000

It will no happened if we change the OS from Debian 8 to Debian 7.