Magento Add to cart in Upsell Product

Magento by default doesn't show the "Add to CART" Button in Upsell product

just need to add the following code u will get the Add to Cart Button

<button type="button" class="form-button add-to-cart" onclick="window.location='<?php echo $this->getAddToCartUrl($_link) ?>';"> <?php echo $this->__('Add to Cart') ?> </button>