NEC sl1100 paging port configuration. Installing a talk back horn Viking v1048c with valcom talkback control v9941a. Does not engage outbound page. If I put butt set in lin and fo off hook the hor works both ways. If I go off hook on butt set during page from pbx the page will go through. I admit to being weak on this side of the telecom world. Seems I'm missing a piece in front of the talkback controller? Haven't found solution through the internets.