6. STOCKHOLDERS' EQUITY (Details Narrative) - $ / shares	9 Months Ended
	Jan. 31, 2018	Apr. 30, 2017
Common stock authorized	500,000,000	500,000,000
Common stock outstanding	45,257,180	44,014,040
Series E Preferred Stock [Member]
Shares issuable upon conversion	6,826,435
Liquidation preference price per share	$ 25.00
Conversion price per share	$ 21.00
If converted, Series E Preferred stock holders would receive shares of common stock. Common shares to be issued	1,961,619
Each outstanding share that could be converted into common shares	4.18
Stock Incentive Plans [Member]
Shares available for issuance	5,433,646
ESPP [Member]
Shares available for issuance	1,303,770
Warrants [Member]
Shares available for issuance	39,040