I'm having trouble with connecting to the c3.js library. I followed the instructions on c3js.org but it won't work. I used a simple example from the website but it isn't showing a thing. I load like this:

```js
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" type="text/css" href="../css/c3.css">

<script src="http://d3js.org/d3.v3.min.js" charset="utf-8"></script>
<script src="../js/c3.min.js"></script>

</head>
<body>
<div id="chart"></div>

var chart = c3.generate({
 bindto: '#chart', 
 data: {
   columns: [
     ['data1', 30, 50, 70, 90], 
     ['data2', 20, 40, 60, 80]
   ]
 }
});
</body>
</html>
```

the problem is i can't see a chart. I only see the code i entered starting from my var.
Thank you every one