Microsoft.DiskQuota.1 + PHP

I'm trying to invoke the Microsoft.DiskQuota.1 object using COM in PHP with the following code:

<?

//first line eliminates php errors from backward slashes.
$homespaceLocation = preg_replace('/\//', '\\', "\\server\share\");

//declare quota object with COM
$quota = new COM("Microsoft.DiskQuota.1");

//initialize homespace
$quotaUser = $quota->Initialize($homespaceLocation, 1);

?>

Which results in the following error:

Warning: (null)(): Invoke() failed: Exception occurred. Source: Unavailable

I was just curious if anyone has used (successfully) the diskquota object to retrieve quota information about users in PHP.

System Information:

Windows 2000 Advanced Server with IIS 5 (SRP applied).
PHP 4.3.0

Any help would be appreciated. Thanks.