Same material different result within object Prologue:
Minor issue that I do not seem to figure out, I've modeled room with some basic things that i've created from the scratch but now there is weird issue with wallpaper material.





Description:
All of the 3 walls are part of the same box object, they have same material and they have been uv mapped the same way on same scale yet the wall on the right displays on grey color instead of the white like the 2 others.

Steps taken:
I've deleted the wall with the issue, recreated it, uv mapped the whole thing again and ended up with the same results. Also went through recreating the material with same result. Checked the direction of normals.

Plea for help:
Any ideas what might cause this, still new to the cycles so would appreciate the insight to the problem so I can learn from it.

Thank you in advance.
Solution:
After fiddling around for while with the issue, recreating and mapping the room also redoing the material and lights ending up with the same problem. The solution to the problem was adding a normal map node in between the Image texture and Diffuse BSDF

Result:


Thank you everyone for input, hope this helps out someone in the future.