Is the the only service you’re having issues with? If not, Have you both cut-in and changed the brakes to lead on the engineers main screen? Have you waited sufficient time for the breaks to release across the whole train? You shouldn’t be moving until both the front and rear brake pressure is up to at least 70 psi, which could take up to 10 minutes or more for some of the longer trains. Matt explains all this in each of the streams on Sherman Hill, so you could watch a replay for tips and tricks
Make sure all the breaks are released, that the reverser is in forward, don't forget to activate the BANKING COMM to use the rear locomotives and go check if the rear locomotives work. Also check all the three types of breaks to be fully released.
Three switches (engine run, generator field, controls) on? Brake cut in and lead? PTT enabled if distributed power? Reverser forward? Released automatic brake and waited until brake pipe pressure on left screen is acceptable?