No USB FET was found when debugging MSP430F5438 Experimenter board

Hi,

I was trying to debug MSP430F5438 Experimenter board using CCSv5, but it says No USB FET was found. I found someone said USB Interface MSP-FET430UIF is needed for debugging. I used to debug MSP430 launchpad successfully without using a debug interface, so do I need MSP-FET430UIF to debug MSP430F5438 Experimenter board? If so, why MSP430 launchpad does not require that?

Thanks!