Railworks America

I never saw this error before, and I'm not sure what is causing it:
I have cars sitting at the Altoona Wwd platform, and I want the engine to hook up to them. The engine is parked on the same track as Wwd Platform, but east of the cars. The driver is to switch to a passing track, and then hook up to the west end of the consist.
Everything looks okay in the editor, but when I start the scenario, I get the following error:

Driver 'Service1' at Lat 40.51550 Long -78.39925 - Missing Marker - Altoona Wwd Platform

not sure what I am doing wrong

Check the rail car numbers you are having it hook up to you may have a number typed incorrectly or missing a car that there is a number for but it is usually due to the fact that you are telling it to take a car that does not exist to a place that does