It's not unusual to not identify with an aspect of your astrology chart. Each program we use to look up and calculate the natal chart has it's own quirks. It's possible that being a Scorpio Sun, you have three or more planets in Scorpio, and none expect the Moon in Sag, and the other planets just overshadow the Sag Moon. Or sometimes when the Moon is full in Sag, you may feel it more. Also, you could have a few more planets of the ten in a different sign than Sag. Why not try Cafeastrology.com or Astrothemes.com, and see if both give you a Sag Moon?