Product Sku on iphone theme

Hi,

I’m trying to display product sku on iphone theme without success.
This is my code on jm_sterix_iphone/template/catalog/list.phtml:

PHP Code:

<div class="product-shop">

                                <header>

                                    <h1><?php echo $_helper->productAttribute($_product, $_product->getName(), 'name') ?></h1>

                                    <?php echo $this->htmlEscape($_product->getSku()); ?><br>

                                    <?php echo $this->getPriceHtml($_product, true) ?>

                                </header>

                            </div>

But it does not display the sku.

Any help?