node.js – grunt错误：找不到模块’load-grunt-tasks’

$ grunt
Loading "Gruntfile.js" tasks...ERROR
>> Error: CAnnot find module 'load-grunt-tasks'
Warning: Task "default" not found. Use --force to conTinue.

Aborted due to warnings.


Execution Time (2015-02-07 18:05:42 UTC)
loading tasks  339ms  ███████████████████████████████████████████████ 99%
@R_991_10586@l 344ms

我已经尝试 – npm安装，npm更新命令。如果有人可以帮助我，这将是巨大的。谢谢！

@L_874_2@Gruntfile.js的内容

'use Strict';

var paths = {
  js: ['*.js','test/**/*.js','!test/coverage/**','!bower_components/**','packages/**/*.js','!packages/**/node_modules/**','!packages/contrib/**/*.js','!packages/contrib/**/node_modules/**'],html: ['packages/**/public/**/views/**','packages/**/server/views/**'],css: ['!bower_components/**','packages/**/public/**/css/*.css','!packages/contrib/**/public/**/css/*.css']
};

module.exports = function(grunt) {

  if (process.env.NODE_ENV !== 'production') {
    require('time-grunt')(grunt);
  }

  // Project Configuration
  grunt.initConfig({
    pkg: grunt.file.readJSON('package.json'),assets: grunt.file.readJSON('config/assets.json'),clean: ['bower_components/build'],watch: {
      js: {
        files: paths.js,tasks: ['jshint'],options: {
          livereload: true
        }
      },html: {
        files: paths.html,options: {
          livereload: true,interval: 500
        }
      },css: {
        files: paths.css,tasks: ['csslint'],options: {
          livereload: true
        }
      }
    },jshint: {
      all: {
        src: paths.js,options: {
          jshintrc: true
        }
      }
    },uglify: {
      core: {
        options: {
          mangle: false
        },files: '<%= assets.core.js %>'
      }
    },csslint: {
      options: {
        csslintrc: '.csslintrc'
      },src: paths.css
    },cssmin: {
      core: {
        files: '<%= assets.core.css %>'
      }
    },nodemon: {
      dev: {
        script: 'server.js',options: {
          args: [],ignore: ['node_modules/**'],ext: 'js,html',nodeArgs: ['--debug'],delayTime: 1,cwd: __dirname
        }
      }
    },concurrent: {
      tasks: ['nodemon','watch'],options: {
        logConcurrentOutput: true
      }
    },mochaTest: {
      options: {
        reporter: 'spec',require: [
          'server.js',function() {
            require('meanio/lib/core_modules/module/util').preload(__dirname + '/packages/**/server','model');
          }
        ]
      },src: ['packages/**/server/tests/**/*.js']
    },env: {
      test: {
        NODE_ENV: 'test'
      }
    },karma: {
      unit: {
        configFile: 'karma.conf.js'
      }
    }
  });

  //Load NPM tasks
  require('load-grunt-tasks')(grunt);

  /**
   * Default Task
   */
  grunt.hook.push('clean',-9999);
  grunt.hook.push('concurrent',9999);
  if (process.env.NODE_ENV === 'production') {
    grunt.hook.push('cssmin',100);
    grunt.hook.push('uglify',200);
  } else {
    grunt.hook.push('jshint',-200);
    grunt.hook.push('csslint',100);
  }

  //Default task.
  grunt.registerTask('default',['hook']);

  //Test task.
  grunt.registerTask('test',['env:test','mochaTest','karma:unit']);

  // For Heroku users only.
  // Docs: https://github.com/linnovate/mean/wiki/deploying-on-Heroku
  grunt.registerTask('heroku:production',['cssmin','uglify']);
};