Thank you for taking the time to write to us, but this is not
a bug. Please double-check the documentation available at
http://www.php.net/manual/ and the instructions on how to report
a bug at http://bugs.php.net/how-to-report.php

output is correct. $objXML is document element

According to the specs:
> Always returns an array of SimpleXMLElement objects.

While the xpath() is actually returning a boolean value.  Here is some revised code which demonstrates an incorrect return value:

<?php
    require_once('inc.backend.interactive.php');
    header('Content-Type: text/plain');
    set_time_limit(0);
   
    $ResponseBody = '<?xml version="1.0" encoding="UTF-8"?><postresponse><status accept="no">INVALID</status></postresponse>';
   
    $objXML = new SimpleXMLElement($ResponseBody);
   
    $tMatches = $objXML->xpath('postresponse/status/@accept');
    print_r($tMatches);
    print_r(gettype($tMatches));
//    print_r((string)$tMatches[0]);
?>

Rob, you didn't get away that easy. :)

re-classifying as documentation issue. xpath() returns boolean on failure.

This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.

"Returns an array of SimpleXMLElement objects or FALSE in case of an error."