Doing a search for /acro_add turned up 1 result, when set to 1 year, and all forums.
The result is
this thread If I open it, all the posts are there, but they are empty, no text, and this shows on the top of the screen:
Warning: Unknown modifier 'a' in /home/www/showflat.php on line 856
Warning: Unknown modifier 'a' in /home/www/showflat.php on line 856
Warning: Unknown modifier 'a' in /home/www/showflat.php on line 856
Warning: Unknown modifier 'a' in /home/www/showflat.php on line 856
Greets