7. INCOME TAXES (Details 2)	12 Months Ended
	May 31, 2014	May 31, 2013	May 31, 2012
Reconciliation of Federal Statutory Rate to Effective Rate
U.S. federal statutory tax rate	34.00%	34.00%	34.00%
State taxes, net of federal tax effect	4.70%	(0.40%)	(0.20%)
Foreign rate differential	(11.90%)	0.20%	2.90%
Stock-based compensation	34.50%	(4.40%)	(6.00%)
Research and development credit	(20.50%)	3.00%	0.10%
Change in valuation allowance	(45.80%)	(33.00%)	(30.20%)
Other	1.30%	(0.30%)	(0.20%)
Effective tax rate	(3.70%)	(0.90%)	0.40%