Which channels are the freqs. in? They must be in specific channels - not 1, 2, 3 etc.
There are 8 freqs. in the Marshall site. The first one must be in channel 7 and the last is in channel 22. Many channels must be left empty.
After entering the last freq., hit SCAN. Then it will start trunking.
Also, if it's trunking, so should never hear the control channel "buzz".