hi all ...
no body seems to be asnwering. im gonna answer my self 😃
when you use ulrewrite and xoad, dpending on the url rwwrite rules, actual path to XOAD you gave inside php file gets rendered differently. so just refer to error message from firefox (because it gives a detailed message) and modify your path accordingly.
you should consider this link to change the path ..
<?= XOAD_Utilities::header('/path/to/xoad') ?>
my application works fine with urlrewrite and xoad