What is the full name of the non-sales employee who made the most number of rejected purchase orders?
non-sales employee refers to PersonType = 'EM'; rejected purchase order refers to Status = 3;
SELECT T2.FirstName, T2.LastName FROM PurchaseOrderHeader AS T1 INNER JOIN Person AS T2 ON T1.EmployeeID = T2.BusinessEntityID WHERE T2.PersonType = 'EM' AND T1.Status = 3 GROUP BY T2.FirstName, T2.LastName ORDER BY COUNT(T1.PurchaseOrderID) DESC LIMIT 1