shell_exec() command

Hi, I have a problem, I didn't know who to email, can you please help me. I am trying to execute a command using PHP, however it gives me the following error: Warning: Cannot execute using backquotes in safe mode in /home/virtual/site1/fst/var/www/html/test.php on line 3 The code that I have is as follows <html><body> <? $output = shell_exec("ls al > zxxzx"); echo "<pre>$output</pre>"; ?> </body></html> I have checked the safe mode option in /etc/php.ini file and it is set to 'Off', therefore I do not know why it gives an error. I was hoping that you could help me. The exec() command does not give an error, but doesn't work. Please help Thank you