heroku failed to run files from static folder in node code example

Example: heroku failed to run files from static folder in node

{
    "name": "bla",
    "version": "0.0.1",
    "dependencies": {
        "express": "3.2.6"
    },
    "engines": {
        "node": "0.10.11",
        "npm": "1.2.25"
    } 
}