file_exists() not working correctly?

Good morning list, I have a _very_ simple function... it is as follows /**********************************************/ function getgalimage($fzg) { $folder = "bilder"; $imgname = $fzg."_1.JPG"; $checkimg = $folder."/".$imgname; if(file_exists($checkimg)) { //echo '<img src="mod_search_thumbs.php?bild='.$imgname.'&fzg_nr='.$fzg.'">'; echo '<img src="'.$checkimg.'">'; } else { echo '<div style="display:block; padding:2px; border:1px solid red;"><a href="'.$checkimg.'">'.$checkimg.'</a></div>'; } } /**********************************************/ Now, the folder "bilder" exists, and I pass the number 0002822 to the function. Now it should check whether the image file "bilder/0002822_1.JPG" exists. It never finds the image, even though it exists (I checked it many times now) Could you point out the obvious mistake I am making here? I have checked it over and over again, and can't find any mistake. I know that sometimes you get stuck in your code, and don't see the obvious. So I'd like to ask you all to show me my error :o) I hope you can see something which I can't. Thanks for your help!! Chris