How return variable from simple smart contract

Hello I’m trying to make my first and simple test for get a variable from my first contract:

Truffle version: Truffle v4.1.14
Node: 8.12.0

pragma solidity ^0.4.4;

contract SimpleContract {
  bytes32  hello = "hello";
  function getHello() public view returns (bytes32){
    return hello;
  }
}

And I did a simple test like:

pragma solidity ^0.4.4;

import "truffle/Assert.sol";
import "truffle/DeployedAddresses.sol";

import "../contracts/SimpleContract.sol";


contract TestSimpleContract {

  function testGetHello() public {
    SimpleContract w = SimpleContract(DeployedAddresses.SimpleContract());
    bytes32  expected = "hello";
    bytes32  hello = w.getHello();

    Assert.equal(hello,expected, "SHould hello!");
  }
}

And I have a Migrations:

var Simple = artifacts.require("SimpleContract");


module.exports = function(deployer) {
  deployer.deploy(Simple);
};

And I have this truffle config

module.exports = {
   networks: {
     development: {
      host: "localhost",
      port: 7545,
      network_id: "5777"
    }
   }
 };

But I can’t understand and how figure out why it return this error:

1) TestSimpleContract
testGetHello:
Error: VM Exception while processing transaction: revert
at Object.InvalidResponse (C:UsersLorenzoAppDataRoamingnpmnode_modulestrufflebuildwebpack:~web3libweb3errors.js:38:1)
at C:UsersLorenzoAppDataRoamingnpmnode_modulestrufflebuildwebpack:~web3libweb3requestmanager.js:86:1
at C:UsersLorenzoAppDataRoamingnpmnode_modulestrufflebuildwebpack:packagestruffle-providerwrapper.js:134:1
at XMLHttpRequest.request.onreadystatechange (C:UsersLorenzoAppDataRoamingnpmnode_modulestrufflebuildwebpack:~web3libweb3httpprovider.js:128:1)
at XMLHttpRequestEventTarget.dispatchEvent (C:UsersLorenzoAppDataRoamingnpmnode_modulestrufflebuildwebpack:~xhr2libxhr2.js:64:1)
at XMLHttpRequest._setReadyState (C:UsersLorenzoAppDataRoamingnpmnode_modulestrufflebuildwebpack:~xhr2libxhr2.js:354:1)
at XMLHttpRequest._onHttpResponseEnd (C:UsersLorenzoAppDataRoamingnpmnode_modulestrufflebuildwebpack:~xhr2libxhr2.js:509:1)
at IncomingMessage. (C:UsersLorenzoAppDataRoamingnpmnode_modulestrufflebuildwebpack:~xhr2libxhr2.js:469:1)
at endReadableNT (_stream_readable.js:1064:12)
at _combinedTickCallback (internal/process/next_tick.js:139:11)
at process._tickCallback (internal/process/next_tick.js:181:9)

> ganache-cli -i 5777