To listen to one of the MuxCo multiplexes on an older DAB Digital Radio you need to do a ‘full retune’.
To do this you may need to do something more than just pressing the ‘Autotune’ button which often just does a ‘quick’ retune. To do a full retune you may need to go into the options or settings part of you radio and do a ‘full retune’.
There’s more information about how to do that at the Digital Radio UK website.