filter empty message

Hi,

I found in one of the posts on this forum the solution to put a message when the filter output is empty (gives no results):
change in product / listing.php:

if(empty($html)){ ?>
to
if(empty($html)){echo 'Geen resultaten met deze filter, gelieve uw filter aan te passen!';} else { ?>

This works indeed when I have an empty filter result, i get this message. But it seems I also get this message when I go to the details page of a product. Always underneath I can find the sentence 'Geen resultaten met deze filter, gelieve uw filter aan te passen!'
Can you please tell me how to solve this?

WBr, Luc