While using Prentice-Hall's TestGen, I exported a test in the Blackboard 6.0-9.0 format. When I tried to import it into Moodle 2.1+, I selected the Blackboard v6, uploaded the zip file and received the following message:

ImportRequired field

The type of the file you selected (application/zip) does not match the type expected by this import format (text/plain).