连接mongodb数据库失败问题

mongodb版本3.2，node安装的mongodb驱动模块版本为1.4.15，顺便问一句Failed to load c++ bson extension, using pure JS version，这个安了bson、node-gyp毫无效果

C:\Users\Administrator\blog>node app.js
Failed to load c++ bson extension, using pure JS version
Express server listening on port 3000
C:\Users\Administrator\blog\node_modules\connect-mongo\lib\connect-mongo.js:178
          throw err;
          ^
Error: Error connecting to database: failed to connect to [localhost:27017]
    at null.<anonymous> (C:\Users\Administrator\blog\node_modules\connect-mongo\
node_modules\mongodb\lib\mongodb\connection\server.js:553:25)
    at emitThree (events.js:97:13)
    at emit (events.js:175:7)
    at null.<anonymous> (C:\Users\Administrator\blog\node_modules\connect-mongo\
node_modules\mongodb\lib\mongodb\connection\connection_pool.js:140:15)
    at emitTwo (events.js:87:13)
    at emit (events.js:172:7)
    at Socket.<anonymous> (C:\Users\Administrator\blog\node_modules\connect-mong
o\node_modules\mongodb\lib\mongodb\connection\connection.js:512:10)
    at emitOne (events.js:77:13)
    at Socket.emit (events.js:169:7)
    at emitErrorNT (net.js:1250:8)