Accounts receivable (Details) (USD $)	Jan. 31, 2013	Apr. 30, 2012
Notes to Financial Statements
Trade receivables	$ 2,349,532	$ 2,620,461
VAT receivable	158,517	184,314
Allowance for doubtful accounts and sales returns	200,000	200,000
Accounts receivable	$ 2,308,049	$ 2,604,775