"Can not load "coverage", it is not registered!" error when running

I install karma-coverage like this: npm install karma-coverage --save-dev

I have a package file that contains this: “devDependencies”: { “karma”: “0.10.2”, “karma-coverage”: “0.1.5”, “karma-junit-reporter”: “0.1.0”, “karma-jasmine”: “0.1.3”, “karma-chrome-launcher”: “0.1.0”, “karma-ie-launcher”: “0.1.1”, “karma-safari-launcher”: “0.1.1”, “karma-firefox-launcher”: “0.1.0” },

And a config file that looks contains this: // test results reporter to use // possible values: ‘dots’, ‘progress’, ‘junit’, ‘growl’, ‘coverage’ reporters: [‘dots’, ‘junit’, ‘coverage’],

preprocessors: {
  // source files, that you wanna generate coverage for
  // do not include tests or libraries
  // (these files will be instrumented by Istanbul)
  'jstarget/**/*.js': ['coverage']
},

// configure the coverage reporter
coverageReporter: {
  type : 'html',
  dir : 'coverage/'
},

And I get an error that looks like this: WARN [reporter]: Can not load “coverage”, it is not registered! Perhaps you are missing some plugin?

What do I need to do?