Undefined variable event after importing variables file

[fpoirier1]

I wanna use semantic-ui for my project. I've copy the less files in the semanticfolder and I have my less where I customize the theme. My src/assets folder looks like this :

- images
- less
  - main.less
- semantic
  - definitions
  - themes
  - semantic.less
  - theme.config
  - theme.less

My gruntFile.js for the less module looks like this :

less: {
  development: {
    files: {
      '<%= config.assets %>/css/main.css' : '<%= config.assets %>/less/main.less',
    }
  }
}

Am I missing something here ?