Animation of Child Objects Are Lost Through FBX Export

I am trying to import a helicopter animation into Poser from Blender via FBX. The helicopter’s main body is a parent of the main rotor and the tail rotor. I cannot figure out why the animations for the main rotor and the tail rotor of the helicopter fail to be imported into Poser. Here is a video showing my problem:

https://youtu.be/Knf0oUo8DGo

Does anyone know why this is happening?