Conditional IIf Formula Help - Microsoft Community

hi have formula want enter query getting error message. logic formula check valid values field 16 given condition of field 15:

if field [15] y, field [16] can y or n, if field [15] n, [16] must na. return ok if these conditions met, if not met, return "error"

here attempt of formula getting error message saying formula has many arguments. advice appreciated.

received: iif([15])="y",([16])="y" or ([16])="n" or iif([15])="n", ([16])="na","ok","error")

try --

received: iif([15] ="y" , ([16]="y" or [16] ="n"), "ok",  iif([15] ="n" , [16]="na","ok","error"))

Office / Access / Windows other / Office 2013