porque la funcion solamente es jecutada una sola vez y no cada vez que la llamo?

[saymon]

Me crea un thumbnail, coloco aqui el contenido:

Código PHP:

   function createthumb($name,$filename,$new_w) 
  { 
          $type = 0; 
          $size = getimagesize($name); 
          $mime = $size['mime'];                    //get image mime type (ex. "image/jpeg" or "image/gif") 
          $system=explode("/",$mime); 
          if (preg_match("/jpg|jpeg/i",$system[sizeof($system)-1])) {$type=1; $src_img=imagecreatefromjpeg($name);} 
          if (preg_match("/png/i",$system[sizeof($system)-1]))      {$type=2; $src_img=imagecreatefrompng($name);} 
          if (preg_match("/gif/i",$system[sizeof($system)-1]))      {$type=3; $src_img=imagecreatefromgif($name);} 
          $old_x=imageSX($src_img); 
          $old_y=imageSY($src_img); 
    
          $thumb_w=$new_w; 
          $thumb_h=($old_y*$new_w)/$old_x; 
           
          $dst_img= imagecreatetruecolor($thumb_w,$thumb_h);          //create new image "canvas"        
          imagecopyresampled($dst_img,$src_img,0,0,0,0,$thumb_w,$thumb_h,$old_x,$old_y); 
          if      ($type == 3)  imagegif($dst_img,$filename);  
          else if ($type == 2)  imagepng($dst_img,$filename);  
          else                  imagejpeg($dst_img,$filename);  
          imagedestroy($dst_img);  
          imagedestroy($src_img);  
  }