Redeemable Common Stock and Stock Purchase Warrants (Tables)

6 Months Ended

Oct. 31, 2013

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:

	October 31,	April 30,
	2013	2013
Expected term in years	2.4 & 4.2	2.9 & 4.7
Risk-free interest rates	0.5% & 1.1%	0.3%
Volatility	91% & 107%	95% & 98%
Dividend yield	0%	0%