Problems with exec and sendfax

Hallo ! i have some problems when trying to use senfax from halyfax within php. i am using php4 on a redhat 6.2 box with the recent version of hylafax and apache. well, i am using the following code: $fd = fopen($tmpPath . $delivery_number, "w"); set_file_buffer($fd, 0); $size = fwrite($fd, $sFax); $result = fclose($fd); $sFax = "/usr/bin/sendfax -n -d 10050732314517 " . $tmpPath . $delivery_number . ""; exec($sFax, $result, $errno); this returns the $errno 255. I also found the following entry in the http-error-log: /tmp/99472343: Can not determine file type when i call the sendfax command from the shell (even as user nobody) it works fine.... does anyone know something about this ? thank you ! otto brandstaetter ps: please also let me know your answers under otto@liwest.at, as i am not subscribed to the mailing list and i do not check the newsgroup regullary..... thank you !