Can anyone please tell me why this [jsFiddle](http://jsfiddle.net/4NwZ9/) doesn't work?

The idea is simple is just suppose to input the selected text into the textbox..

**HTML:**

```
<input type="text" id="teste" maxlength="50">
<select>
    <option onClick="nelson">nelson</option>
</select>

```

**JavaScript:**

```
function nelson(){
    document.getElementById('teste').value =+ "nelson"; 
}

```

Thanks in advance