Mecanim aniamtion error

Hi

My artist build a archer fbx for our game with animation like run,idle,attack.

After imported to mecanim, we find it acts weird when switch from attack to idle/run, his bow and arrow stayed at wrong position (mid-air)rather than his hands. Attack animation is quite simple, open his bow and shoot a arrow away. Unity throw exceptions like these:

 !IsFinite(outDistanceForSort)

 !IsFinite(outDistanceAlongView)

 !IsFinite(outDistanceForSort)
 UnityEditor.DockArea:OnGUI()

 !IsFinite(outDistanceAlongView)
 UnityEditor.DockArea:OnGUI()

Any help? Thank you :)

Actually I just find that rig for attack has a little bit different with others, could this be the key?