Breaks in a gradient colour scale

Hello,

I want to make the colour gradient white from -3-3 and red and blue. However, I cannot seem to get the breaks recognised, e.g. so from +3 it starts going red, and negative -3 it starts going blue. I think i need to use the breaks function but I cannot get it working.

below is the bit i am having a issue with

Hi, remember put a reproducible example of data, for better undestand and all the communty could help you in a better way.

Other easy way is put the result when you make this.

dput(populations[1:30, ])