Problem when picking up cars and train starts automatically

[glenn68]

I am in the works making a standard scenario for the NS Coal district route with RSC SW1500's and Great Northerners P&LE 14 panel coal hoppers. I have the two SW1500's start off in brownsville approaching the yard but have to cross onto the bridge to make a turn around to back into the yard to pick up the hoppers but when I connect to the hoppers the train starts to move forward automatically out of control. What do I need to do to correct this?

Thanks,
Glenn Blum