viz.grab() on subobjects

[NASA GRC]

I'm using the viz.grab() function such that the user's virtual hand can grab objects in the scene, or just subobjects of a model, and pull them apart.

When I use the call to grab the top level of a model's scene graph, it works just fine, the model is linked to the hand. However, when I use the call to grab a subobject (as modeled in an external modeling package, NOT created as a child in vizard code), it doesnt work very well. The subobject is clearly selected and being transformed, however it doenst link rigidly to the hand, but rather it seems to rotate around its local origin in place rather than moving with the hand.

Has anyone else seen this? Whats going on here? Any fixes?

Thanks.