3. EARNINGS PER SHARE (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Feb. 28, 2018	Feb. 28, 2017	Feb. 28, 2018	Feb. 28, 2017
Earnings Per Share [Abstract]
Numerator: Net income (loss)	$ 267	$ (2,651)	$ 337	$ (4,858)
Denominator for basic net income (loss) per share: Weighted average shares outstanding (in thousands)	21,832	16,672	21,631	15,411
Shares used in basic net income (loss) per share calculation (in thousands)	21,832	16,672	21,631	15,411
Effect of dilutive securities (in thousands)	809	0	1,207	0
Denominator for diluted net income (loss) per share (in thousands)	22,641	16,672	22,838	15,411
Basic net income (loss) per share	$ 0.01	$ (0.16)	$ 0.02	$ (0.32)
Diluted net income (loss) per share	$ 0.01	$ (0.16)	$ 0.01	$ (0.32)