The only things that would cause a vehicle not to appear if they were added to the vehicles list and made active are:
1. You may have created one or more Schedule Views and so the new vehicle you've added is not included in the Schedule View. To check this, open the Schedule, right-click, choose Schedule Views and be sure that if there is a schedule view listed there, that you add the new vehicle to any and all views that you want the vehicle to be included in.
2. You may have added one or more absences to the Vehicle on the Absences tab of the Vehicle setup screen that is making that vehicle be unavailable for the date range you are viewing. Go to Misc/Setup > Vehicles, choose the Vehicle that won't appear on the Schedule, and then on the Absences tab, delete any Absence records there.
Other than those exceptions, it is pretty simple to add a new vehicle column to the schedule view. Go to Misc/Setup > Vehicles, click Add New Vehicle, enter a description, and click OK. If you want there to be a picture of the vehicle at the top of the column, then you also need to click the Load button there on the Status tab of the Vehicle screen and browse and choose the picture file, but that is not required for the column to show on the schedule.
