Hi Mikey,
I uploaded the code you had there to the functions.php file of my active template; there is nothing else in that file except what it came with. I put it directly under the <?php tag, but it still didn’t work. I went to a product’s page, and it seemed like there weren’t any related products there for a second, then they loaded in. Do you know why this might be happening? Could it possibly have to do with my hosting service, or something?