mail_cron.php doesn't work

Requirements: MySQL, PHP5, Webserver Apache/2.0.46 (CentOS)
Apache-CronJob is installed and works (proofed by logs):
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#!/bin/bash
 cd /home/httpd/vhosts/DOMAIN.com/httpdocs/DIRECTORY_1/DIRECTORY_2
 ./mail_cron.php
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The problem seems to be in the script mail_cron.php (see below).
As programmer says it works on a Linux-server, but it doesn't execute on Apache.
Who can tell-me something about the possible reason?

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#!/usr/bin/php
<?php

$path=str_replace('/subscribers','',$_SERVER['PWD']);
define("D_INCLUDES", $path . "/includes/");

      require_once "../includes/hall.php";      
      require_once "../includes/template.class.php";
      require_once "../includes/mail.php";

$connection = DB::connect($dsn, true);
if (DB::isError($connection)) {
      trigger_error($connection->getMessage(), E_USER_ERROR);
}

$query="select mem_sub_id sub_id, memo.ID mem_id, sub_language
            from memo, subscribers
            where (mem_expiry=now()-interval 10 day or mem_expiry=now()-interval 1 month)
                        and mem_sub_id=subscribers.ID order by sub_language";

//echo "\n\n\n $query                        \n\n\n";
$result = $connection->query($query);
      if (DB::isError($result)) {
            trigger_error($result->getMessage(), E_USER_ERROR);
      }
while ($row = $result->fetchRow(DB_FETCHMODE_ASSOC))
{
      $sl=$row['sub_language'];
      if ($sl!=$_SESSION['lang'])
      {
            $_SESSION['lang']=$sl;
            LoadLangSpecific();      
      }
      $sub_id=$row['sub_id'];
      $mem_id=$row['mem_id'];
      MailConfiramtion($sub_id, $mem_id, T_COMMEMORATE);
}
?>
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Thanks for any help!
Otto