7. EQUITY COMPENSATION PLANS (Details - Share based compensation) - USD ($)	3 Months Ended		6 Months Ended
	Oct. 31, 2016	Oct. 31, 2015	Oct. 31, 2016	Oct. 31, 2015
Share based compensation	$ 885,000	$ 1,274,000	$ 1,722,000	$ 2,457,000
Stock Options [Member]
Share based compensation	823,000	1,223,000	1,554,000	2,347,000
ESPP [Member]
Share based compensation	62,000	51,000	168,000	110,000
Cost of contract manufacturing [Member]
Share based compensation	24,000	9,000	66,000	22,000
Research and development [Member]
Share based compensation	446,000	569,000	816,000	1,040,000
Selling, general and administrative [Member]
Share based compensation	$ 415,000	$ 696,000	$ 840,000	$ 1,395,000