Don't know precisely what I did, but the animation is now working fine !
Just have to resize again the falg by 150 % instead of 200% (which is a bit too big
)
Thank for the help!
Ah ! Another thing : i use wings 3D. Do you know how to move automatically a 3D object by setting the position of one of its vertex ? I would like to move the corner to the origin (i mean where X=0, Y=0, Z=0) for each resized frame of the flag. It's very boring to do that manually for 25 models ...