I'm getting a ref error when I try to create a Surface.

This is the console error:

```
Uncaught Error: Invariant Violation: addComponentAsRefTo(...): Only a ReactOwner can have refs. This usually means that you're trying to add a ref to a component that doesn't have an owner (that is, was not created inside of another component's `render` method). Try rendering this component inside of a new top-level component which will hold the ref.
```

Here's my code:

```
'use strict';

var React = require('react');
var $ = require('jquery');
var ReactCanvas = require('react-canvas');
var Surface = ReactCanvas.Surface;
var Image = ReactCanvas.Image;
var Text = ReactCanvas.Text;

var DropGame = React.createClass({

render: function() {

return (



Here is some text below an image.


);

}
});

module.exports = DropGame;
```

Is there something I'm missing?
Thanks in advance for the help!