CONSOLIDATED STATEMENTS OF STOCKHOLDERS EQUITY (USD $)	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	Total
BALANCES, April 30, at Apr. 30, 2009	$ 46,000	$ 248,215,000	$ (247,360,000)	$ 901,000
BALANCES, April 30, (in Shares) at Apr. 30, 2009	45,537,711
Common stock issued for cash (March 26, 2009)	2,000	6,585,000		6,587,000
Common stock issued for cash (July 14, 2009)	5,000	18,882,000		18,887,000
Common stock issued for cash (in Shares) (March 26, 2009)	1,855,172
Common stock issued for cash (in Shares) (July 14, 2009)	5,643,749
Common stock issued upon exercise of options		105,000		105,000
Common stock issued upon exercise of options (in Shares)	57,253
Fractional shares issued pursuant to reverse stock split (in Shares)	1,011
Share-based compensation		1,421,000		1,421,000
Net loss			(14,494,000)	(14,494,000)
BALANCES, April 30, at Apr. 30, 2010	53,000	275,208,000	(261,854,000)	13,407,000
BALANCES, April 30, (in Shares) at Apr. 30, 2010	53,094,896
Common stock issued for cash (July 14, 2009)	2,000	5,434,000		5,436,000
Common stock issued for cash (June 22, 2010)	9,000	14,645,000		14,654,000
Common stock issued for cash (December 29, 2010)	6,000	12,991,000		12,997,000
Common stock issued for cash (in Shares) (July 14, 2009)	1,925,565
Common stock issued for cash (in Shares) (June 22, 2010)	9,214,373
Common stock issued for cash (in Shares) (December 29, 2010)	5,224,491
Common stock issued upon exercise of options		44,000		44,000
Common stock issued upon exercise of options (in Shares)	20,750
Common stock issued upon exercise of warrants (in Shares)	74,802
Common stock issued for services		60,000		60,000
Common stock issued for services (in Shares)	28,921
Common stock issued under restricted stock awards (in Shares)	148,500
Common stock issued under Employee Stock Purchase Plan		134,000		134,000
Common stock issued under Employee Stock Purchase Plan (in Shares)	104,844
Share-based compensation		2,837,000		2,837,000
Net loss			(34,151,000)	(34,151,000)
BALANCES, April 30, at Apr. 30, 2011	70,000	311,353,000	(296,005,000)	15,418,000
BALANCES, April 30, (in Shares) at Apr. 30, 2011	69,837,142
Common stock issued for cash (December 29, 2010)	25,000	26,739,000		26,764,000
Common stock issued for cash (September 2, 2011)	6,000	6,409,000		6,415,000
Common stock issued for cash (in Shares) (December 29, 2010)	24,873,930
Common stock issued for cash (in Shares) (September 2, 2011)	6,252,252
Common stock issued under Employee Stock Purchase Plan		236,000		236,000
Common stock issued under Employee Stock Purchase Plan (in Shares)	458,041
Share-based compensation		2,769,000		2,769,000
Net loss			(42,119,000)	(42,119,000)
BALANCES, April 30, at Apr. 30, 2012	$ 101,000	$ 347,506,000	$ (338,124,000)	$ 9,483,000
BALANCES, April 30, (in Shares) at Apr. 30, 2012	101,421,365