++++ 1 . Own resources of the European Communities - Post-clearance recovery of import or export duties - Amount of duties not collected equal to or greater than ECU 2 000 - National authorities seeking to effect recovery - Duty to refer the matter to the Commission - None ( Council Regulation No 1697/79, Art . 5(2 ); Commission Regulation No 1573/80, Art . 4 ) 2 . Own resources of the European Communities - Post-clearance recovery of import or export duties - Error by the administration which "could not reasonably have been detected by the person liable" - Criteria for assessment ( Council Regulation No 1697/79, Art . 5(2 ) )