Problem with partially UV-unwrapping a simple object Blender 2.8/Eevee,

As I've proven to myself time and time again, my texturing knowledge and skills are  abysmal...

I want to texture a part of my object with a custom texture but I can't seem to get it working. I've tried reading and watching tutorials but I believe I'm doing exactly what the tutorials say and still nothing.

Im trying to put a custom texture ONLY on the top of the counter (as indicated by the names of the material slot and UV map), I've unwrapped only that portion and used nodes to create what should have been a working material (the rest of the object is divided into other materials, by the assign button). However, nothing but the default color can be seen in rendered view. What am I doing wrong?
I found the problem.

Apparrently in 2.8 you can't just add image texture nodes and link everything up like I used to do in older Blender versions. Blender will only read a texture if it's imported through the properties panel, next to the color picker button. Thought I'd try to do the exact same steps that are shown in the tutorial (even though they result in exactly the same node structure) and it worked, but trying to build an identical node setup somehow fails...