ie7 Magento下拉數量不接價值

我已經添加了一個量子字段是我們商店的一個下拉的格式，它在firefox，chrome，ie9，ie8上工作正常，但未能在ie7上獲取值。ie7 Magento下拉數量不接價值

任何人都可以幫忙嗎？

下面是代碼

<?php $_product = $this->getProduct() ?> 

<?php if($_product->isSaleable()): ?> 
<div class="ptyre_price floatleft botm"> 
    <p> 
    <?php $incTax = Mage::helper('tax')->getPrice($_product, $_product->getFinalPrice(), 2);   
    echo $this->__(Mage::helper('core')->currency($incTax)); 
    ?></p><span class="price-each-text">Each</span> 
</div> 
<div class="product-buttons"> 
<form action="<?php echo $this->getAddToCartUrl($_product) ?>" method="post"  id="product_addtocart_form"> 
QUANTITY: 

<select name="qty" id="qty" class="qty"> 
<option value="1">1</option> 
<option value="2">2</option> 
<option value="3">3</option> 
<option value="4" selected>4</option> 
<option value="5">5</option> 
<option value="6">6</option> 
<option value="7">7</option> 
<option value="8">8</option> 
</select> 
<button class="form-button" onclick="productAddToCartForm.submit(this)"><span><?php echo $this->__('BUY'); ?></span></button>  
</form> 

</div> 
<?php endif; ?> 
<script type="text/javascript"> 
    var productAddToCartForm = new VarienForm('product_addtocart_form'); 
    productAddToCartForm.submit = function(inVal){ 
      this.form.qty.value = inVal; 
      if (this.validator.validate()) { 
        this.form.submit(); 
      } 
    }.bind(productAddToCartForm); 
</script>

來源

2011-12-14 James Dickinson