How do you get on top of the train in mystery train?

You go into the luggage room and there is a door at the top now open

depends which stage

Before you can start the detective quest, you have to walk through the whole train and speak to all of the passengers and crew. Once you speak to everyone, go to Thomas Edison's cabin to see his...

once you get out of your balloon, go to the left until you see this guy standing next to some suitcases. Help the guy with the suitcases and he will give you a train ticket. Then, go to the train and...

you have to figure out who stole the camera.