Minifying pipeline doesn't work

I've added the minifying pipeline in the user/config/system.yaml
assets: # Configuration for Assets Manager (JS, CSS)
css_pipeline: false # The CSS pipeline is the unification of multiple CSS resources into one file
css_minify: true # Minify the CSS during pipelining
css_rewrite: true # Rewrite any CSS relative URLs during pipelining
js_pipeline: false # The JS pipeline is the unification of multiple JS resources into one file
js_minify: true # Minify the JS during pipelining

It does nothing. What else do I have to configure for this to work?

I figured out why. I need to set the pipeline-vars to "true". Only then the other features get activated.