another gl morphing topic

hi all ,
after many searches , without managing to understand what's wrong , what i'm missing ,
here's my question .

i'm trying to morph between two jit.gl.model , using xfade .
quite a classic on this forum , i know , but ....
here is a simple patch ,
at its simplest :

and i also join a zip file containing this same patch ,
and two simple objects made in blender .
first object is a basic cube , second object is this same cube , with a displacement applied to an edge .
it's a very basic transform , done in one time , then export obj. file .
the 2 objects have the same amount of vetices, faces ...

BUT ,
as you can see in the patch , they don't morph like i would like they did .
faces are flying as we "xfade" , and land somewhere else on the destination mesh .

of course i would like them to stay in place ,
i woud like to see the modified edge growing , as we "xfade" ,
and only this . (hope i'm clearly explaining)

i think i have tried all settings i could on the render object , on the jit.gl.model objects ,on the xfade object , ....
i have tried many things in blender (format files , minimum editing on mesh, ..)
i have also tried to look at the obj. files in textedit (mac) ,
but still can't find how to make this holy grail happen !

is the displacement the cause , even a so small and simple displacement ?

anyway ,
thanks to the many people here , who 've already made me learn so much ...

cheers
Matthieu