adsence showing in preview but not on blog

Hi,
I am having trouble with adsence. I am using the following code to display adsence on my blog:

Class in CSS: –

.ads {
float: left;
}

Code in ‘single post’ file: –

<div class=”postnavigation”>
<div class=”right”>
<?php next_post(‘ % »’,”,’yes’) ?>
</div>
<div class=”left”>
<?php previous_post(‘« %’,”,’yes’) ?>
</div>
</div>
<div class=”singlepost”>
<div class=”title” id=”post-<?php the_ID(); ?>”>
” rel=”bookmark”>
<?php the_title(); ?>

</div>
<h3><span class=”posted”><?php _e(“Posted on “); ?></span>
<?php the_time(‘l j F Y’,display); ?>
</h3>

<div class=”ads”>
<script type=”text/javascript”><!–
google_ad_client = “pub-4483569516064961”;
google_ad_width = 300;
google_ad_height = 250;
google_ad_format = “300x250_as”;
google_ad_type = “text_image”;
google_ad_channel = “”;
//–>
</script>
<script type=”text/javascript”
src=”https://pagead2.googlesyndication.com/pagead/show_ads.js”&gt;
</script>
</div>

I the preview section of my blog post it displays perfectly, but when the blog is published no adsence is displayed.

What am I doing wrong?

Thanks in advance.

Tim.