I am very new to Houdini and am having a problem with exporting a simple animation to Unity, using FBX. I've simplified it down to very simple network to illustrate. It's very similar to the soccer ball example in the Foundations PDF. See the attachments for two pictures of the network.

I am using 2 null nodes to animate simple geometry. One of them is referenced by a transform to rotate a component within in the network.

I am achieving the desired result in Houdini. The animation successfully imports into Maya.

In Unity, the rotations animated by the RotateTop null are lost and do not show up. Making RotateTop a parent of the geo1 node solves the problem, but obviously then rotates more than what I want rotated.

I would appreciate any insights. Thank you!