Organization, Use of Estimates and Basis of Presentation (Details) (USD $)	3 Months Ended		9 Months Ended
	Jan. 31, 2015	Jan. 31, 2014	Jan. 31, 2015	Jan. 31, 2014
Basic loss per share computation
Net loss attributable to common stockholders	$ (2,816,000)	$ (574,000)	$ (9,463,000)	$ (5,134,000)
Weighted Average common shares - basic	66,893,364	66,867,114	66,890,929	66,860,792
Basic net loss per share	$ (0.04)	$ (0.01)	$ (0.14)	$ (0.08)
Diluted loss per share computation
Net loss attributable to common stockholders	(2,816,000)	(574,000)	(9,463,000)	(5,134,000)
Less: Gain on derivative warrant liability	620,687	845,774	1,401,314	0
Loss available to common stockholders	$ (3,437,152)	$ (1,419,981)	$ (10,863,595)	$ (5,133,684)
Weighted Average common shares	66,893,364	66,867,114	66,890,929	66,860,792
Incremental shares from assumed exercise of warrants and stock options	352,213	0	352,213	0
Adjusted weighted average share - diluted.	67,245,577	66,867,114	67,243,142	66,860,792
Diluted net loss per share	$ (0.05)	$ (0.02)	$ (0.16)	$ (0.08)