Redeemable Common Stock and Stock Purchase Warrants (Tables)

12 Months Ended

Apr. 30, 2014

Redeemable Common Stock and Stock Purchase Warrant [Abstract]

Schedule of Share-based Payment Award Stock Warrants Valuation Assumptions [Table Text Block]

Assumptions used to calculate the fair value of these warrants were as follows:

	Year Ended April 30,
	2014	2013
Expected term in years	1.9 - 3.7	2.9 - 4.7
Risk-free interest rates	0.4% - 1.17%	0.3%
Volatility	95% - 113%	95% - 98%
Dividend yield	0%	0%