This script work to place ads in the middle of your content/post. You can use it :
Dont Forget to Parse your HTML here : HTML Parse Tools. Next, you replace "PUT YOUR ADS CODE with your ads code.
<div expr:id='"post1" + data:post.id'/><div class='googlepublisherads' style='margin:20px 0'>
<!--YOURADS CODE-->
<center/></div><div expr:id='"post2" + data:post.id'><data:post.body/></div><script type='text/javascript'>var obj0=document.getElementById("post1<data:post.id/>");var obj1=document.getElementById("post2<data:post.id/>");var s=obj1.innerHTML;var t=s.substr(0,s.length/2);var r=t.lastIndexOf("<br>");if(r>0) {obj0.innerHTML=s.substr(0,r);obj1.innerHTML=s.substr(r+4);}</script>
Tel me when the script does not work