Displacement not working properly - following Blender Guru rope tutorial this is my first post so let me know if I'm doing something wrong. 

I'm following this Blender Guru tutorial: https://youtu.be/1drRNphACMc?t=955

At the 15:55 mark he changes Displacement to True, which I've done, but my result doesn't look like his. Everything up until this point has, and I can't see any differences between what he's done and what I've done. 

Mine looks like this instead: 



And when he adds a Subdivision Surface modifier, it gets more bumps which make it look more ropey, but mine just goes back to looking completely smooth, like so:



Any advice on where I might be going wrong here?
You might have to set your displacement map to non color data in the node editor. 

Here is an example of microdisplacement with the map set to color data:



And this is the same image, set to non color data: