I want to draw a center line like the red dashed line in the image below, but I can't create it.

As you can see in the image, even if you execute the "Centerline" command and click on the two parallel lines where you want to draw the centerline,
As you can see in the blue border of the image, I get the error "Cannot create centerline based on selected entity" and cannot create centerline.

How can I create a centerline?