Digitrax Zephyr xtra Manual page 35

If your MU could not be set up you will see the following error message:
This happens when you try to link to an address that is already part of an MU
or link an address that is under the control of another throttle. For example if
you MUed address 14 to the top loco 23 and then tried to MU another address
to 14 you would get this error. If you wanted to add another loco to the MU
with 23 as the TOP address, the right way to do it is to add that loco to 23, not
to another address in the MU.
©2012 Digitrax, Inc. www.digitrax.com 34