[Unity 4.3] Skinned legacy animations do not work

Greetings. I've got a really awkward problem.

I'm creating an FPS game of sorts, and I decided I'd use the UFPS pack in order to save some time. However, using that pack requires that animations, such as a firearm's reloading anim, be marked as Legacy. I created a couple of animations (using MAX), and flagged them as Legacy as instructed, however they do not play correctly for whatever reason. The animations consist of the gun movement (whilst firing and reloading), which was made without using bones, and the player's arms, which were done through a biped and IK blending in order to follow the gun, i.e. they do have bones. Now, when I look at the Inspector for the .fbx file, both animations play out correctly and the arms follow the gun and do whatever they should. However, when played through an "Animation" component, the (bone-using) arms are static and only the (boneless) gun animates.

I am indeed baffled by this. I tried researching the problem, but nothing works for me.

Does anyone know why this happens and what I can do to resolve it? Thanks in advance.