The WPLib has a problem in RobotDrive where m_isCANInitialized is never updated to TRUE. Because of this the Black or Grey Jaguars are never sent the joystick values in order to update the output of the speed controllers. To fix this you can create your own RobotDriveFixed class that extends RobotDrive. In your class update the m_isCANInitialized to true. Here are some threads that have helped determine this:
http://www.chiefdelphi.com/forums/showthread.php?t=132817&highlight=m_isCANInitializ ed
http://www.chiefdelphi.com/forums/showthread.php?t=132651&highlight=m_isCANInitializ ed