[ODE] composite object split

[Guillaume Jouffroy]

Hello,

I have built up a composite object, which is made of 2 pieces, a box, 
and on top of it sits a trimesh. I can perfectly move this geom around 
on the ground. However when I put the object in the air and let it fall 
down, when it gets to the ground, its pieces split, as if they were not 
"glued" together. Could you please give me any clue about what I am 
doing wrong ?

Thank yoooouuuuu !

Guillaume