7. EQUITY COMPENSATION PLANS (Details)	12 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2011
Option Grant
Risk-free interest rate	0.96%	1.44%	2.09%
Expected life (in years)	5 years 10 months 6 days	5 years 11 months 1 day	6 years
Expected volatility	95.87%	74.08%	73.42%
Expected dividend yield	0.00%	0.00%	0.00%
Shares purchased under the 2010 ESPP
Risk-free interest rate	0.15%	0.06%	0.15%
Expected life (in years)	6 months	6 months	6 months
Expected volatility	167.36%	67.96%	82.72%
Expected dividend yield	0.00%	0.00%	0.00%