help!! I can't get the lines to work on a nec electra elite 48,I have a coi4 card in slot 3 and have it programmed in slot assignments,I also have the line keys programmed for co lines,I have swapped out the card and it still does not work,it will not ring in if i call the line ,and if i press the line key it displays"error",I went through the manual and do not see what I am missing,can anyone please help