do_shortcode() problem (or bug)

This is my shortcode:

function add_div($atts, $content = null) {
	$class = shortcode_atts( array('class' => 'default_class'), $atts );
	return '<div class="'.$class['class'].'">'.$content.'</div>';
}
add_shortcode("add_div", "add_div");

I’m trying to use this on page template:
<? echo do_shortcode('[add_div class="some_class"]Some text[/add_div]'); ?>

And it return something like that:

<div class="some_class"></div>
CONTENT GOES HERE

I want it to make it like this:
<div class="some_class">CONTENT GOES HERE</div>

The problem is that it doesn’t parse [/add_div] element.

It makes it correct (it parses [/add_div]) when my shortcode is placed on some page or in post but it doesn’t work in template file.
Please help!