关于composer的问题 [ 2.0 版本 ]

代码报如下错误是啥原因呀？

$ composer require "lujian/yii2-wechat:*"
./composer.json has been updated
Loading composer repositories with package information
Updating dependencies (including require-dev)
Your requirements could not be resolved to an installable set of package

  Problem 1
    - The requested package lujian/yii2-wechat could not be found in any
, there may be a typo in the package name.
  Problem 2
    - The requested package pjkui/kindeditor could not be found in any v
there may be a typo in the package name.

Potential causes:
 - A typo in the package name
 - The package is not available in a stable-enough version according to
imum-stability setting
   see <https://groups.google.com/d/topic/composer-dev/_g3ASeIFlrc/discu
or more details.

Read <https://getcomposer.org/doc/articles/troubleshooting.md> for furth
n problems.

Installation failed, reverting ./composer.json to its original content.