Adding auto text in post title

[zurih]

Maybe someone can help me on this..
I managed to remove the minimum characters requirement if the user posts a reply.
Now, I want that when the user replies to the thread only with a title, there will be an addon to it. So it can be recognized as a 'only title post'.

I asked for something like that in here:
https://vborg.vbsupport.ru/showthread.php?t=74362

I added this:

PHP Code:

if($_POST['message']==null){$_POST['subject']=$_POST['subject']." blahblahblah";} 


but its not working..

Thanks in advance