The problem in the game (Assassin's Creed: Syndicate)

The problem is probably,that did not play consistently.Given the task to stop the train.The player got to the train.Was the job of the machinist to put out the fire on the cars.Managed perfectly.It is necessary to separate the cars.And the problem here.One as it is disengaged, and the other player comes and not shown the letter E, to perform.In the beginning when the player jumped on the train.Did the job.I did the command to jump off the train.The train left and played in the city.What do I do can someone tell me.Thanks in advance!