STOCK-BASED COMPENSATION (Details 3) - Warrant [Member] - $ / shares	3 Months Ended
	Aug. 31, 2015	May. 31, 2015	May. 31, 2014
Shares outstanding	4,776,320	3,937,986	2,401,043
Weighted-average remaining life	3 years 1 month 17 days
Weighted-average exercise price (in dollars per share)	$ 1.55	$ 1.45	$ 1.34
Number exercisable	4,776,320
$1.20 [Member]
Exercise price range, upper range limit (in dollars per share)	$ 1.20
Shares outstanding	3,004,656
Weighted-average remaining life	4 years 1 month 20 days
Weighted-average exercise price (in dollars per share)	$ 1.20
Number exercisable	3,004,656
$2.00 [Member]
Exercise price range, upper range limit (in dollars per share)	$ 2.00
Shares outstanding	1,671,664
Weighted-average remaining life	2 years 11 months 26 days
Weighted-average exercise price (in dollars per share)	$ 2.00
Number exercisable	1,671,664
$3.00 to $6.00 [Member]
Exercise price range, lower range limit (in dollars per share)	$ 3.00
Exercise price range, upper range limit (in dollars per share)	$ 6.00
Shares outstanding	100,000
Weighted-average remaining life	1 year 5 months 23 days
Weighted-average exercise price (in dollars per share)	$ 4.50
Number exercisable	100,000