why it still says : Cannot find module 'creationix'?

[luckypoem]

hi.

as3:/howtonode.org-site# npm install creationix
npm WARN package.json cluster@0.7.7 cluster is also the name of a node core module.
npm http GET https://registry.npmjs.org/creationix
npm http 304 https://registry.npmjs.org/creationix
npm http GET https://registry.npmjs.org/send
npm http 304 https://registry.npmjs.org/send
npm http GET https://registry.npmjs.org/fresh/0.2.0
npm http GET https://registry.npmjs.org/debug
npm http GET https://registry.npmjs.org/mime
npm http 304 https://registry.npmjs.org/debug
npm http GET https://registry.npmjs.org/range-parser/0.0.4
npm http 304 https://registry.npmjs.org/range-parser/0.0.4
npm http 304 https://registry.npmjs.org/fresh/0.2.0
npm http 304 https://registry.npmjs.org/mime
creationix@0.4.0 node_modules/creationix
└── send@0.1.4 (fresh@0.2.0, range-parser@0.0.4, debug@0.7.4, mime@1.2.11)
as3:/howtonode.org-site# node server/server.js

module.js:340
throw err;
^
Error: Cannot find module 'creationix'
at Function.Module._resolveFilename (module.js:338:15)
at Function.Module._load (module.js:280:25)
at Module.require (module.js:364:17)
at require (module.js:380:17)
at Object. (/root/howtonode.org-site/server/server.js:3:18)
at Module._compile (module.js:456:26)
at Object.Module._extensions..js (module.js:474:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Function.Module.runMain (module.js:497:10)
as3:~/howtonode.org-site#

how to fix it?thank u