Steam Br143 - What Is The Correct Procedure?

So I drove the Dosto cab car to Meissen, then I need to change ends to drive back to Dresden in the BR143.

Can somebody explain the correct procedure in the game for shutting down the cab in the Dosto and then departing in the BR143? I thought I did everything correctly, but the train simply would not move.

 

When you shut down the dosto cab was the brakes released.