Are you sure you are applying the command to the correct child entity within the animmesh? I think the base part is not that actual mesh itself - you need to use GetChild to find the mesh - then try the MeshHeight command on that child object.
So, try this -
See if that (or some variation on that) returns any sensible values.
Also you could try loading the mesh as a normal mesh and not an animmesh and see it the commands work then (also try this with your problem about linepick) - then you will narrow it down to the animated mesh causing the problem (and I still suspect you are not finding the correct child object) and you can work from there.
So, try this -
mesh = LOADANIMMESH("file.b3d") debuglog countchildren(mesh) child1 = getchild(mesh,1) debuglog countsurfaces(child1)
See if that (or some variation on that) returns any sensible values.
Also you could try loading the mesh as a normal mesh and not an animmesh and see it the commands work then (also try this with your problem about linepick) - then you will narrow it down to the animated mesh causing the problem (and I still suspect you are not finding the correct child object) and you can work from there.