The Bluechart maps are unlocked to a different GPS device. nRoute recognizes the 20x and sees the serial number does not match the device the maps are unlocked to.
If you use GPS Gate, it will see your 20x and put out an nRoute-friendly data stream to a COM port. The serial number of the 20x will be masked and nRoute should be happy when set to look at that COM port.
GPS Gate is available as a free 30 day trial. If it does the job, you can purchase the light version, GPS Gate Express for a good price.
Terry