I created a Network Dataset and use our Centerline feature class. I brought in the Networked Dataset into arcMap and created a Service area which created the six classes, all of which are empty except for the Facilities feature class, which I managed to load the three fire stations within our city limits. I have gone into the Properties of the Service Area Group Layer and updated the Polygon Generation and updated the Impedence to Minutes and the Default Breaks to show 1, 2, 3, 4, 5, 6, 7 within the Analysis Settings, but nothing happens when I apply the settings.