Look in the left corner. Is there a silhouette with a Question mark on it? If there is, you need a driver for this train. Go into the "Driver" section of quick drive and click add driver, then assign them to a train. You can also do this in surveyor, but I don't know how. Are you at an interactive industry, if so, if you stop on the industry track your train's controls disappear for a second to 10 seconds or so.
