I was getting the same error message. Then I watched one of the presonus supplied tutorials (by Joe Gilder), and he basically set up the bus a different way. As an example, let's say he had 7 tracks of drums. Instead of highlighting all those tracks, then right clicking "add bus with selected channels", he just added one bus channel under "add bus channel" Then he highlighted each of the 7 drum tracks and clicked on one of the track's output settings, and clicked on the new bus on the drop down list. Voila, routing solve. Granted it should not give us this error by just using the "add a bus using selected channels", but this was a way to get around it and it worked.