product partial

product_partial.php

        <? $this->render_partial('shop:product_options'); ?>        
        <? if (PSInventory_Inventory::out_of_stock( $product, post('product_options') )): ?>
          <p>
            <strong>
              <? $options_string = PSInventory_Data::create_option_string(post('product_extra_options', array()), $product->id);
    		$data = PSInventory_Data::create()->where('product_id=? AND options_string=?', $product->id, $options_string)->find();
     		$extended_sku = $data->extended_sku;
  		?>
  	      We're sorry, the item (size/color/style) you've selected is temporarily out-of-stock. 
             <a href="<?= site_url('out-of-stock-contact-form') ?>?item=<?= urlencode($extended_sku); ?>" rel="lightbox[external 900 300]" title="Out of Stock Contact Form" id="oosLink" class="button">Notify me</a> when this item becomes available.
             </strong>
            <? if ($product->expected_availability_date): ?>  
                <br/>The expected availability date is <strong><?= $product->displayField('expected_availability_date') ?></strong>
            <? endif ?>
          </p>
        <?  endif ?>
      </div>

Phil, the code you posted didn't seem to return any values. I moved it to where I would it like it to perform it's magic -- on the product_partial.php. But, it highlights the line "$extended_sku = $data->extended_sku;" and says "Trying to get property of non-object"