I need to know the file size of remote file, but never be able to do it.

One of the my example PHP Script:

<?php
     $location = "http://www.blockm.com/admin.gif";
     $fp = fopen($location,"w");
     //$fp = file_exists($location);
     if(!$fp) {$message = "File not found";}
     else {$message = "File Found";
           $temp = fstat($location);
           $image = GetImageSize ($location);
     }
     echo "$message<br>";
     echo "File Size: " . $temp[7] . "<br>";
     echo "Image Size: $image[3]<br>";
     fclose($fp);
?>

The above script can working properly for reading local file.

NB: I am doing project for Banner exchange. I want to
put all the banner immage on remote Server. 

Regards
Eko