In 3DS Max, you have to sample the animation before exporting.
Choose the number of keyframes to create.
E.g, for an animation running from frame 1 to 1000, selecting 1 keyframe
every then frame will sample the animation to 100 keyframes. Then you can
export to Shockwave 3D.
This method is also used when creating a spline based animation in 3DS Max
as splines are not supported by the exporter.