Here's my node.js file I'm running on Heroku. It works perfectly locally, but when I push it to Heroku, the database collection isn't created and no errors are thrown. Ultimately I'm just trying to get it to actually creating the connection while it's running on Heroku. Thanks.

var mongoose = require('mongoose'),
    db_url = process.env.MONGOHQ_URL || "mongodb://john:@staff.mongohq.com:10053/app3305538",
    db = mongoose.connect(db_url),
    Schema = mongoose.Schema;

//Mongoose DB Test
var MsgSchema = new Schema({
    date: {type: Date, default: Date.now},
    message: String
});
var MsgModel = db.model("messages", MsgSchema);
var Msg = new MsgModel();
Msg.message = "blurgh";
Msg.save();

Did you specify node version in heroku?

please refer this. ( I also confused same issue. but resolved.) http://devcenter.heroku.com/articles/nodejs-versions