Php Facebook开放图错误-推断属性&；对象缺少必需的值

我知道论坛上已经有很多关于FB开放图的问题。每件事我都看了很多遍。我只是不明白为什么当一切似乎都与FB和其他人所说的一致时，我会继续犯上述错误。 这是header.tpl中的内容

        <!-- Facebook Meta Tags -->
        <meta property="og:url" content="<?php echo $base; ?>/index.php?
        route=product/product&product_id=<?php echo $product_id;?>" />
        <meta property="og:type" content="website" />
        <meta property="og:title" content="<?php echo 
        $product_heading_title; ?>" />
        <meta property="og:description" content="<?php echo 
        $product_description; ?>" />
        <meta property="og:image" content="<?php echo $product_thumb; ?>" />
        <meta property="website:section" content="Product share offers" />

         <meta property="website:published_time"  content="<?php echo 
         strtotime('now'); ?>" /> 
         <meta property="website:modified_time"  content="<?php echo 
         strtotime('+30min'); ?>" /> 
         <meta property="website:tag"  content="Facebook" /> 
         <meta property="website:tag" content="Products" /> 





        <meta name="twitter:card" content="product">
    <meta name="twitter:site" content="@publisher_handle">
    <meta name="twitter:title" content="<?php echo $product_heading_title; ?
    >">
    <meta name="twitter:description" content="<?php echo 
    $product_description; ?>">
    <meta name="twitter:creator" content="@author_handle">
    <meta name="twitter:image" content="<?php echo $product_thumb; ?>">



        <meta property="og:title" content="<?php echo 
       $product_heading_title; ?>" />
        <meta property="og:description" content="<?php echo 
       $product_description; ?>" />
        <meta property="og:image" content="<?php echo $product_thumb; ?>" />

        <!-- Google+ Meta Tags -->      
        <link href="https://plus.google.com/" rel="publisher">
        <meta itemprop="name" content="<?php echo $product_heading_title; ?
        >">
        <meta itemprop="description" content="<?php echo 
        $product_description; ?>">
        <meta itemprop="image" content="<?php echo $product_thumb; ?>">


    <?php 
} 
?>