iview按需引入时报错

These dependencies were not found:

* iview/dist/styles/iview.css in ./src/main.js
* iview/src/components/button in ./node_modules/babel-loader/lib!./node_modules/vue-loader/lib/selector.js?type=script&index=0!./src/components/HelloWorld.vue

To install them, you can run: npm install --save iview/dist/styles/iview.css iview/src/components/button

main.js

// The Vue build version to load with the `import` command
// (runtime-only or standalone) has been set in webpack.base.conf with an alias.
import Vue from 'vue'
import App from './App'
import router from './router'
import { Button } from 'iview'
import 'iview/dist/styles/iview.css'

Vue.config.productionTip = false
Vue.component('Button', Button)

/* eslint-disable no-new */
new Vue({
  el: '#app',
  router,
  components: { App },
  template: '<App/>'
})

.babelrc

{
  "presets": [
    ["env", {
      "modules": false,
      "targets": {
        "browsers": ["> 1%", "last 2 versions", "not ie <= 8"]
      }
    }],
    "stage-2"
  ],
  "plugins": ["transform-vue-jsx", "transform-runtime", [
    "import", {
      "libraryName": "iview",
      "libraryDirectory": "src/components"
    }
  ]]
}

Hello.vue

<template>
  <div class="hello">
    <Button type="primary">Primary</Button>
  </div>
</template>

• 我是按照最新的官方api来引入的，下面的插件已经引入了

npm install babel-plugin-import --save-dev

麻烦看下什么原因，谢谢~