I have stared too long on this apparently not working little piece of code. Why doesn't select box rel attribute get alerted?

HTML:

```
<select rel="prop216" name="prop[]">
  <option value="">- none</option>
  <option value="12">Opt 1</option>
  <option value="13">Opt 2</option>
</select>
<select rel="prop217" name="prop[]">
  <option value="">- none</option>
  <option value="12">Opt 1</option>
  <option value="13">Opt 2</option>
</select>

```

jQuery:

```
$("select").change(function()
{
 var i = 0;
 var alteredSelects = [];
 $("select").each(function()
 {
    if ( $(this).val() !== "" )
    {
        alteredSelects[i][0] = $(this).attr('rel');
        alteredSelects[i][1] = $(this).val();
        alert ($(this).attr('rel'));
        i++;

    }
 });
});

```

See also my jSfiddle: <http://jsfiddle.net/ft6Bd/1/> 

I get an error in Firefox 

> 
> TypeError: can't convert undefined to object 
> 
> 
> 

on the line `alteredSelects[i][0] = $(this).attr('rel');`

But can't seem to realize why.