404 Not found error while assigning dynamic permissions

Hello,

I am having an issue with assigning users to groups in dynamic permissions. I get a "404 Not Found" error on this file "adminmembers.php", but incidentally when I go back to the permissions page the user's permissions are assigned. I see that the file name looks odd and incomplete and that may be why it throws the error. I had this error when I was using IIS 7.5 on Zend Server Community Edition, but even when I switched to Apache with the same Zend server I still get the error. Initially I thought it had to do with modrewrite, which I know IIS does not handle as good as Apache, but as I said, I still have the error. Please anyone kindly help me sort it out.

Thank you.