How can I import a blendshape animation using fbx file format exported from motionbuilder?

Here is what we are trying to do:

We are capturing full body and facial motion using appropriate devices in MotionBuilder 2014. We are doing all the capture at the same time to avoid synchronization problems.

We export body motion as bone animations and face animations as blendshape animations through FBX format. Unity sees the animations fine, however when it comes to facial blendshape animations, it fails to play the animation. All the blendshape keys become bright red in the Animation view which I suppose indicates there is no mapping between animation curves and blendshapes. (The mapping should have been automatic I think)

We have already tried to import using FBX 2011/2012 formats and baked animations checked while exporting(What we actually do is we export from motionbuilder to Maya for more advanced export settings). By the way the animation plays fine in Maya.

So the question is this: How do we properly make a blendshape animation recorded in Motionbuilder work in Unity using FBX file format(or any other format which can be converted from FBX)?

Thank you, Melih