express中怎么通过mongoskin连接mongodb，我的老报错[Error: invalid schema, expected mongodb]

E:\nodejs\myapp>npm ls mongodb [email protected] E:\nodejs\myapp └── [email protected] extraneous

npm ERR! extraneous: [email protected] E:\nodejs\myapp\node_modules\mongodb

E:\nodejs\myapp>npm ls mongoskin [email protected] E:\nodejs\myapp └── [email protected] extraneous

npm ERR! extraneous: [email protected] E:\nodejs\myapp\node_modules\mongoskin

E:\nodejs\myapp>npm ls jade [email protected] E:\nodejs\myapp └── [email protected]