MSP430Flasher.exe -n MSP430F2618 -r [main.hex,MAIN] -v main.hex
save it with INFO, BSL and even RAM too to complete.
above is a command that works for me everytime. It only shows unknown device error if the JTAG connection was wrong (Is the target self powered and did you connect its Vcc to the FET Vcc_Target (and Vcc_Tool unconnected)? Also not connecting both FEt and Target to same ground wire can produce the error).
If the format is correct and it won't run yet will run in FET-Pro430, then I am clueless.
Let others who know why help.