[LW] [LW11] S100 Pairing issue

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A friend on our marina has bought separately on Ebay an rf controller and a separate s100 control unit from different sellers. I know they are sold and paired by Raymarine together, however I also know from a distant past experience that you can register to a different rf controller from the dealer setup menu as explained in the manual. When I try to go into setup mode I get the the message" setup unavailale" I also tried to do this in my workshop by applying 12v to the seatalk red and braid terminals of the rf unit and without an autopilot to connect to it makes no difference I guess because they are not paired. I have opened the rf unit and the yellow led is coming on initially but the handset sees no rf on its sig strength bar
Any ideas? Do I need a pilot connected? TIA