Hi there,
There are a lot of factors that may have affected your score. How did you feel about timing? Is there a certain type of question that you feel gave you the most trouble? Do you feel as though you got tough questions thrown at you at the beginning of the test that you had trouble with? If you have even an inkling of an idea, you can focus on improving these areas. I do agree that it would be quite disappointing to score 100 points below your best sim test, and I have a feeling that you are capable of achieving a higher score your next go-around -- if you can determine exactly what the issue was.