17. SELECTED QUARTERLY CONSOLIDATED FINANCIAL DATA (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	May 31, 2016	Feb. 29, 2016	Nov. 30, 2015	Aug. 31, 2015	May 31, 2015	Feb. 28, 2015	Nov. 30, 2014	Aug. 31, 2014	May 31, 2016	May 31, 2015	May 31, 2014
Selected Quarterly Consolidated Financial Data Details
Net sales	$ 1,571	$ 1,677	$ 4,620	$ 6,633	$ 1,818	$ 2,027	$ 2,615	$ 3,558	$ 14,501	$ 10,018	$ 19,684
Gross profit	(98)	169	1,691	3,383	682	852	694	1,610	5,145	3,838	10,222
Net (loss) income	$ (3,056)	$ (2,975)	$ (1,048)	$ 294	$ (1,900)	$ (1,726)	$ (2,114)	$ (907)	$ (6,785)	$ (6,647)	$ 422
Net (loss) income per share basic and diluted	$ (0.23)	$ (0.23)	$ (0.08)	$ 0.02	$ (0.15)	$ (0.14)	$ (0.18)	$ (0.08)	$ (0.52)	$ (0.55)	$ 0.04