Why this tab doesn't work?

I have added this tab in my page but I can't send invite to my friends. It doesn't work !! Why ? I have used this code:

<?php $url_inc="<fb:req-choice url='http://facebook.com/Anti.Social.Development' label='Partecipa' />"; ?>


<center>
<fb:fbml> 
<fb:request-form
action="index.php" 
method="POST" 
invite="true" 
type="InvitoSpeciale" 
content="Ti invito <?php echo htmlentities($url_inc); ?> " > 
<fb:multi-friend-selector cols="3" rows="3" showborder="false" actiontext="Invita i tuoi amici."> 
<fb:request-form-submit />
</fb:request-form> 
</fb:fbml>
</center>

<fb:share-button class="meta">
<meta name="medium" content="mult"/>
<meta name="title" content="name of fan page"/>
<meta name="description" c开发者_如何学编程ontent="description of fan page"/>
<link rel="image_src" href="url to image location" />
<link rel="target_url" href="http://facebook.com/Anti.Social.Development"/>
</fb:share-button>

Hello Senior as for as I have understood you are closing extra one ">" bracket after your content heading. For me the below code works

<fb:serverFbml width="760px">
  <script type="text/fbml">
    <fb:fbml>
      <fb:request-form
            action='http://apps.facebook.com/yoursite/'
            method='POST'
            type='photo fun'
            content="Let's fun with facebook
        <fb:req-choice url='http://www.yoursite.com' label='Register'/>"
        <fb:multi-friend-selector actiontext="Select your friends."></fb:multi-friend-selector>
     </fb:request-form>
   </fb:fbml>
  </script>
</fb:serverFbml>