Adsense ad placement question

i want to place a large rectangle ad under the post title of my blog.But it shows a blank space when i do it
The code is:

<script type="text/javascript"><!--
google_ad_client = "pub-XXXXXXXXXXXXXXX";
google_alternate_color = "FFFFFF";
google_ad_width = 468;
google_ad_height = 60;
google_ad_format = "468x60_as";
google_ad_type = "text";
google_ad_channel ="XXXXXXXXXX";
google_color_border = "FFFFFF";
google_color_bg = "FFFFFF";
google_color_link = "5C6AA6";
google_color_url = "0080C0";
google_color_text = "000000";
//--></script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>

When i remove <!-- and --> from the code it shows the ad as needed

Then the code becomes:

<script type="text/javascript">
google_ad_client = "pub-XXXXXXXXXXXXXXX";
google_alternate_color = "FFFFFF";
google_ad_width = 468;
google_ad_height = 60;
google_ad_format = "468x60_as";
google_ad_type = "text";
google_ad_channel ="XXXXXXXXXX";
google_color_border = "FFFFFF";
google_color_bg = "FFFFFF";
google_color_link = "5C6AA6";
google_color_url = "0080C0";
google_color_text = "000000";
//</script>
<script type="text/javascript"
src="http://pagead2.googlesyndication.com/pagead/show_ads.js">
</script>

I want to know what should i do?Since its against adsense tos to modify the code is there any other way to insert the code without modifying it to get desired results?

 

Which blog CMS u r using? and can u show me the url or a sample.
see my blog in wp do u want something like this one? I added code manually in template file header. blog in my recent blog list