php exprt for exec function issue -- 2

HI, I have one linux binary file which returns text from image. I use exec php function to get result text. But issue is if i use same image on different location, the returning result is not same. Do you know the reason? Please bid only if you know the reason. thanks in advance. Here is my php code. $base_dir = __DIR__; $enginePath = $base_dir.'/../../bin'; //$imagePath = $base_dir."/../[login to view URL]"; $imagePath = $base_dir.'/../../aaa/[login to view URL]'; $cmd = $enginePath.' ' . $imagePath; exec ($cmd, $output); echo $output[0];