Why not: "It may not" ?
As far as I know ''It may not'' is used to express uncertainty. "Het mag niet'' simply means something is not allowed.
Strictly, that is incorrect. "May not" meaning "is not allowed to" is good English, though rather antiquated and rarely used.
belachelijk, it may not, het mag niet. je mag hier niet camperen.. you may not camp here... its the same come on.
The "o" in the infinitive changes to "a". Is this common?