Work order for an mri? What?

Hello all. I was just curious. My husbands got a workers comp case nearing close—the other side’s team said that he should have gotten a MRI and told him to schedule. He tried and they said no that was the other sides responsibility if they wanted it done; they didn’t write an order for it. So today an imaging center called regarding the MRI and told him, “we cannot schedule one because the doctor did not provide a work order.” So they’re just going to go on with the case without it. Work order? What? We are so confused