The “the_content” hook not working !

Hi everyone,

First of all, excuse my english. I’m doing the best I can.

I’m new to plugins. I had a look yesterday into “the_content” hook. I’ve done something simple with it and is not working at all (I will provide an example below). I also tried it on a fresh 2.5.1 version and worked perfectly BUT, when I upgraded to 2.5.1 from 2.3.1, has stopped to work.

Let’s say I have the following code:

function my_content_filter($content_to_filter)
{
$top = "My plugin was here...";
$bottom = "...and here too.";

return $top . $content_to_filter . $bottom;
}
add_filter('the_content', 'my_content_filter');

Ok, I know, this is a fairly simple one but when I activate it and refresh a single post or my home page, I get no results. The content still unmodified ??

Any advices are welcome… I’ll be very grateful to you.

Thanks!