使用magento获得产品重量

I'm trying to make a csv export script, for a partener price aggregation sistem. i'm having trouble extracting the weight of the products from magento.

$show_prodweight = (@$_GET['weight'] == "on") ? "on" : "off";
....
$product = Mage::getModel('catalog/product');
$product->setStoreId($storeId);
$product->load($product_id);

$prod_model = $product->getSku();   
$prod_id = $product->getId();
$prod_name = $product->getName();

if ( $show_prodweight =="on") {
    $prod_weight = $product->getWeight ();
    }
    else {
    $prod_weight == "2";
    }
....
print $PRODUCT['prod_weight'] . $datafeed_separator . 

Can someone please tell me what i am doing wrong ?

resolved it by simplyfing code

$product = Mage::getModel('catalog/product');
$product->setStoreId($storeId);
$product->load($product_id);

$prod_model = $product->getSku();   
$prod_id = $product->getId();
$prod_name = $product->getName();
$prod_weight = $product->getWeight();