Line tool

Maybe there is a basic misunderstanding: 

Photoshop’s Line Tool does not create »lines« like you might be familiar with from Illustrator but polygons (without arrow-heads that would be »plain« rectangles). 

So you get an enclosed area (colored with the Fill) and a countour to which you can apply a Stroke. 

Sorry, forgot the link: 

https://www.take-a-screenshot.org

Please post a proper screenshot with the pertinent Panels (Toolbar, Layers, Options Bar, Properties, …) visible.