Warnings & errors not showing up in gutter

[jeromecovington]

I'm expecting warnings and errors to be noted in the gutter when saving a file, as my other linting tools do, but that is not happening.

Here is my .vimrc plugin settings:

" plugin settings
let g:ctrlp_match_window = 'order:ttb,max:20'
let g:NERDSpaceDelims=1
let g:gitgutter_enabled = 0
let g:syntastic_shell = '/bin/bash'
let g:syntastic_javascript_checkers = ['eslint']
let g:used_javascript_libs = 'flux,react,lo-dash'
let g:syntastic_sass_checkers=["sass_lint"]
let g:syntastic_scss_checkers=["sass_lint"]

I have both of these installed:

Plugin 'scrooloose/syntastic'
Plugin 'gcorne/vim-sass-lint'