That clarifies the situation considerably. (Let me mention, I often hazard a partial answer, under uncertainties, with the awareness that it will need to be 'filled in' further in further postings to this case. And I'm aware that I have not yet given a complete answer... owing to uncertainties at my end of the process, as to what the exact situation is. But you have settled those uncertainties, and I apologize for not being able to give a more rapid answer.)
The answer, straight from the manual, is:
press the Zone key,
then press the [Ch up] and/or the [Ch down] key to select the desired zone.
The manual is not without uncertainties: do you hold down the Zone key then push one of the other keys? you know, both keys at once, the Zone key and the Ch up/down key ? it's possible, given the wording.
Then you'd select the Zone by letting go of the Ch up/down key, then letting go of the Zone key - more or less - if that was the case.
Let me know if that works - I'm understandably not quite sure at this point.
If this answers the question rightly, please rate my answer. Thanks, ***** ***** luck.