I am working on a bill approval workflow. There is a custom field on the vendor record called "Default Approver". The workflow should populate the Next Approver field on the Vendor Bill with the person's name from the aforementioned Default Approver field. The Next Approver field fails to populate. Any ideas? I am not experienced in workflows...

Do you know if the workflow is firing at all? That would be the first thing I'd check. Is the workflow running successfully on any other Bill?