INCOME TAXES - Reconciliation of taxes (Details) - USD ($) $ in Thousands	12 Months Ended
	Apr. 30, 2021	Apr. 30, 2020
INCOME TAXES
Computed tax provision (benefit) at statutory rate	$ 2,108	$ (1,603)
Increase (reduction) in tax resulting from:
Deferred tax rate changes	139	163
Change in valuation allowances	(304)	262
State income taxes, net of federal income tax effect	366	(481)
Permanent items	(63)	1
Other	397	(64)
Total provision (benefit) for income taxes	$ 2,643	$ (1,722)