15. Product Warranties (Details) - Schedule of Product Warranty Liability - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2017	Apr. 30, 2016
Schedule of Product Warranty Liability [Abstract]
Balance at beginning of year	$ 557	$ 557
Warranty costs incurred	(159)	(296)
Product warranty accrual	159	296
Balance at end of year	$ 557	$ 557