Why is my SpeedTree asset not moving with wind?

Hi, I use the plugin SpeedTree to make tree and i follow the doc for exporting and importing in UE4 but in UE4 the tree don’t move. I check with the material and the speetree node is corectly connect to the world position offset parameter.
If someone can help me plz it will be great.
Thx.

Add a wind actor to the scene
http://docs.speedtree.com/doku.php?id=working_with_models_in_ue4#wind