pdf mit php versenden

[gp812]

Hi.
Habe folgendes Code:
/////////////////////// anfang //////////////////
  $path = "orders/";
  $send_pdf =  "bestellung_".$newnummer.".pdf";

if($unhappy=true)
  {
          ///////////////////////////////////////
          // pdfs
          $file = $send_pdf;
          $file_name = $send_pdf;
          $from = "[e-mail]";
          $to = "[e-mail]";
          ////////////// message ////////////////////////
          // betreff
          $subject = "pdf-test";
          ////////////// message ////////////////////////
          $message  = "\n\ndrei pdfs als attachment schicken\n\n";
          ////////////// message ////////////////////////
          //////////////// header ///////////////////////
          $boundary = strtoupper(md5(uniqid(time())));
          $mail_header  = "From: <$from>\n";
          $mail_header .= "MIME-Version: 1.0";
          $mail_header .= "\nContent-Type: multipart/mixed; boundary=$boundary";
          $mail_header .= "\n\nThis is a multi-part message in MIME format  --  Dies ist eine mehrteilige Nachricht im MIME-Format";
          $mail_header .= "\n--$boundary";
          $mail_header .= "\nContent-Type: text/plain";
          $mail_header .= "\nContent-Transfer-Encoding: 8bit";
          $mail_header .= "\n\n$message";
          //////////////// header ///////////////////////
          //////////////// attachment1 ///////////////////////
          $mail_header .= "\n--$boundary";
          $mail_header .= "\nContent-Type: application/x-download; name="$file_name"";
          $mail_header .= "\nContent-Transfer-Encoding: base64";
          $mail_header .= "\nContent-Disposition: attachment; filename="$file_name"";
          $file_content = fread(fopen($path.$file,"r"),filesize($path.$file));
          $file_content = chunk_split(base64_encode($file_content));
          $mail_header .= "\n\n$file_content";
          $mail_header .= "\n--$boundary";

//////////////// mail ///////////////////////
          $success = mail($to,$subject,$message,$mail_header);

if($success)
              {
              echo "mail wurde versandt";
              echo "email wurde versendet";
              }
          else
              {
              echo "email wurde <b>nicht</b> versandt";
              }
      }
  else
      {
      // wenn es keine datei gibt, gibt es auch nichts zu versenden
      echo "keine mail versendet, da es keine datei gibt";
      }

/////////////////////// ende //////////////////

Das problem, das die .pdf-datei, die ankommt, ist immer 1KB groß, und ist nucht lesbar. Dutzend andere scripte bringen das gleiche. Woran liegt es?
Danke voraus.