PennDOT has ordered some bus drivers in the Millcreek School District to re-take their commercial driver's license test.

But the district was unaware of the problem until Erie News Now started to ask questions.

Several drivers say they received a letter from PennDOT explaining there was a problem with the way a third-party administered the exam.

For now, the drivers who work for First Student, the district's bus provider, can keep driving.

But they have to take the test again from a PennDOT examiner.

The drivers are not sure what went wrong.

The district is also looking for answers.

Superintendent Bill Hall said, "That is the point of our discussion with First Student, making sure that whomever is doing that testing is doing it appropriately."

We contacted PennDOT but we are still waiting for an explanation.

First student Corporate Communications Manager Jen Biddinger  providing a statement, saying, "PennDOT recently made us aware of concerns involving a third-party tester for commercial driver's licenses. As a result PennDOT  has requested some of our drivers undergo retesting. We are actively supporting them through this process."