[Ethereum] How to access Swarm content from ethereum smart contract using oraclize

I am trying to access the content in a file that I uploaded to Swarm using oraclize. I found a smart contract in https://github.com/oraclize/ethereum-examples/blob/master/solidity/Swarm.sol

I was just trying to print the 'hello world' (the content of the swarm hash the author specified in the contract). So, I simply mined the contract. Then used the details in the JavaScript as follows (using meteor.js):

//variables

contractAddressSwarm = "0x87b620f0731e15cb1655e216a87c986154ba4248"

ABIArraySwarm = [{"constant":false,"inputs":[{"name":"myid","type":"bytes32"},{"name":"result","type":"string"}],"name":"__callback","outputs":[],"payable":false,"type":"function"},{"constant":false,"inputs":[{"name":"myid","type":"bytes32"},{"name":"result","type":"string"},{"name":"proof","type":"bytes"}],"name":"__callback","outputs":[],"payable":false,"type":"function"},{"constant":true,"inputs":[],"name":"swarmContent","outputs":[{"name":"","type":"string"}],"payable":false,"type":"function"},{"constant":false,"inputs":[],"name":"update","outputs":[],"payable":true,"type":"function"},{"inputs":[],"payable":false,"type":"constructor"},{"anonymous":false,"inputs":[{"indexed":false,"name":"description","type":"string"}],"name":"newOraclizeQuery","type":"event"},{"anonymous":false,"inputs":[{"indexed":false,"name":"swarmContent","type":"string"}],"name":"newSwarmContent","type":"event"}]

//Print swarm content in the console when a button is clicked

'click #buttonSwarm'(event, instance) {
var template= Template.instance();

myContract = web3.eth.contract(ABIArraySwarm).at(contractAddressSwarm);

console.log("Swarm Contract execution");

myContract.swarmContent(function(err, res){
TemplateVar.set(template, "counter", res);
console.log(TemplateVar.get(template,"counter"));
});
},

….

But every time it is printing 'null'. What am I doing wrong in the callback?