The audit can come back with problems for many reasons. Sometimes, a course you took was developed after you matriculated at Montclair State and the computer does not recognize it as applicable to your program. Sometimes you mistakenly took a course, thinking it would count for one category when in fact it only counts for another. Sometimes transfer credits were not evaluated.
Take a look at your audit. An official copy came with your letter from the Registrar, but you can also examine your audit with "Analysis of Degree Progress" on WESS.
Take a look all the way at the bottom at "FREE ELECTIVES" - in 90% of cases, the culprit can be found here, instead of in the category where it belongs. In this case, contact the department chair for a credit adjustment.
However, it is also possible you did not take the right courses, or did not take enough courses. For advice on how to remedy your particular case, contact your faculty advisor.