Yep!
The game wont play the animation (or not right at least) unless you tell it to, either through text keys, or in this case, NiBSAnimationNodes.
Open your tree in NifSkope, right click on your animated mesh->Node->Attack Parent Node->NiBSAnimationNode. If you have more than one animated mesh, copy and paste the others into the created node.
Hope that works for you.
edit: The flags for NiBSAnimationNodes are set to 42 on other meshes, not sure if this actually does anything, but you may wish to set yours at 42 as well, just as a precaution.