STOCK-BASED COMPENSATION (Details 2) - Warrant [Member] - $ / shares	9 Months Ended	12 Months Ended
	Feb. 28, 2017	May 31, 2016
Class of Warrant or Right, Number of Warrants [Roll Forward]
Outstanding, beginning	5,225,987	3,937,986
Granted		1,288,001
Exercised
Expired or cancelled	(147,833)
Outstanding, ending	5,078,153	5,225,987
Class of Warrant or Right, Weighted Average Exercise Price of Warrants or Rights [Roll Forward]
Outstanding, beginning	$ 1.53	$ 1.45
Granted		1.78
Exercised
Expired or cancelled	3.43
Outstanding, ending	$ 1.57	$ 1.53