FBIK rigs must be exported from Maya with the current FBX plug-in version. 
Note: If you have the 2012 versions of MotionBuilder and Maya, you can use the single-step interoperability workflows to export FBIK rigs. See 
Send control rigs to Maya. 
 
Note: FBIK rigs exported from Maya with a version of FBX plug-in previous to version 2009.3 require the control rig settings Pull Iteration to be set to 10 to have full body mode. 
To download the latest FBX plug-in:
- Go to http://www.autodesk.com/fbx. 
 
- Click the Downloads link to the left. 
 
- Select the FBX Plug-ins, Converter, and QuickTime Viewer Downloads link. 
 
- Select the latest version of FBX plug-in for the Maya software version you are using.