Common Stock and Stock Purchase Warrants (Tables)

12 Months Ended

Apr. 30, 2015

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,
	2015		2014
Expected term in years		1.1 – 4.9		1.9 – 3.7
Risk-free interest rates		0.5% – 1.76%		0.4% – 1.17%
Volatility		73% – 107%		95% – 113%
Dividend yield		0%		0%