I just received a canceled test result. Do I need to send my driver/employee/ candidate for another test?

Only if the MRO requests it. It depends on why the test was canceled. If it was a Random test, no recollection is required or allowed. If it was a Pre-Employment, Return-to-Duty or Follow-Up test, you need a result, so will have to send the driver again. DOT regulations require that an employee has a [...]