Gulp error

This is my first attemp with Sage…I have tried to run a gulp line command but i get this "strange " error

module.js:339
throw err;
^

Error: Cannot find module ‘dateformat’
at Function.Module._resolveFilename (module.js:337:15)
at Function.Module._load (module.js:287:25)
at Module.require (module.js:366:17)
at require (module.js:385:17)
at Object. (/usr/local/lib/node_modules/gulp/node_modules/gulp-util/index.js:5:9)
at Module._compile (module.js:435:26)
at Object.Module._extensions…js (module.js:442:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:311:12)
at Module.require (module.js:366:17)

I have installed node, bower and gulp…
What is broken? Thank you in advance

Thank you
I have reinstalled the theme and rebuild the node dependencies
Now all work fine
Thank you very mutch