System() do not work

I tried to use the system() function but it does not work.
If I use it locally on my webserver works perfectly!

some help?
<? $stringa="ping 192.168.0.101 -n 1 -w 1"; ob_start(); system($stringa); $cominfo=ob_get_contents(); ob_clean(); echo$cominfo; ?>
thanks

Daniele

We are using the DLL version of PHP, so such system functions are not implemented.
We are trying to implement them for command-line applications built with ExeOutput 2.0.