SQLSTATE[23000]: Integrity constraint violation: 1452 Cannot add or update a child row: a foreign key constraint fails (`mlvcom_mlvstore`.`affiliateplus_account`, CONSTRAINT `affiliateplus_account_ibfk_1` FOREIGN KEY (`customer_id`) REFERENCES `customer_entity` (`entity_id`) ON DELETE CASCADE ON UPDATE CASCADE)

I tried flushing cache but I dont really know Magento that great. Can anyone help?