trying to deploy rinkeby web3 in nodejs server.. giving error: Invalid JSON RPC response: ""

route.js

var socketServer;
var Web3 = require('web3');
var web3 = new Web3();
var coursetroContract;
var coursetro;



exports.initialize = function(socketServer)
{
    socketServer = socketServer;
    //web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));
    web3 = new Web3(new Web3.providers.HttpProvider("https://rinkeby.infura.io/svQrZJFfqBUisljJTEbT"));
    console.log("web3 version: " + web3.version.api);
    //web3.eth.defaultAccount = web3.eth.accounts[0];
    web3.eth.defaultAccount = '0xFc3AdaDD00aA7b5d1f4CE014665685aB0388c5A7';
    console.log("default account balance: " + web3.fromWei(web3.eth.getBalance(web3.eth.defaultAccount).toNumber(), 'ether'))
    coursetroContract = web3.eth.contract([{"constant":false,"inputs":[{"name":"_instructorName","type":"string"},{"name":"_instructorAge","type":"uint256"}],"name":"setInstructor","outputs":[],"payable":false,"stateMutability":"nonpayable","type":"function"},{"constant":true,"inputs":[],"name":"getInstructor","outputs":[{"name":"","type":"string"},{"name":"","type":"uint256"}],"payable":false,"stateMutability":"view","type":"function"},{"inputs":[],"payable":false,"stateMutability":"nonpayable","type":"constructor"},{"anonymous":false,"inputs":[{"indexed":false,"name":"name","type":"string"},{"indexed":false,"name":"age","type":"uint256"}],"name":"InstructorEvent","type":"event"}]);
    coursetro = coursetroContract.at("0xcff4afd5bbb3d7398a149568a50cbc6ca8e7511e");  
    //console.log(coursetro);  //TILL HERE ALL GOOD..
        
    var instructorEvent = coursetro.InstructorEvent(
        {   
            address: '0xcff4afd5bbb3d7398a149568a50cbc6ca8e7511e',
            type: 'event'
        });
    instructorEvent.watch(
        function(error, result)
        {
            if (!error)
            {
                console.log("Now only contract updated with new value!");     
                socketServer.emit("New Instructor Info Event", {name:result.args.name, age:result.args.age});
            }
            else
            {
                console.log("Error from Contract Event: " + error); //I AM GETTING HERE WITH ERROR INVALID JSON RESPONS
            }
        }
    );    
}



//call back function to be called when '/' route is called
exports.home = function(request,response)
{
    var name = "dummyName";
    var age = "dummyAge";
                response.render("home",
                    {
                        title:"My 2nd Dapp",
                        headline:"Instructor Dapp",
                        instructorName:name,
                        instructorAge:age
                    }
                );      
}

exports.update = function(enteredName,enteredAge,enteredAccount,socketServer)
{
    web3.eth.defaultAccount = web3.eth.accounts[enteredAccount];
    coursetro.setInstructor(enteredName, enteredAge,
        (error, response) =>
        {
            if (error)
            {
                console.log("Account is not authorized");
                socketServer.emit("New Error Event", "Account is not authorized");
            }
        }
    );
    console.log("Info update request done successfully");
    return [enteredName,enteredAge];
}