v2.4.0.8
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%