Just to be certain..
1) Ensure that the FTDI usb to serial converter is installed properly. You should see those additional two serial ports in your HW manager.
2) Ensure all switches on SW4 are set to ON
Does it still work (on your last installed application) if you set switch 2 on SW4 to OFF with a power reset?
Can you also use a multimeter to check out the voltages to the chip and EEPROM?
If all fail, then the tag could be bricked.