This is an issue I have when using plugins in conjunction with pages created with bootstrap framework.
I am doing it this way because I want the plugin page to work in its own right. as well as when it is 'plugged-in'.
Thanks for finding the cause of the problem.
I now see it is the line
<?php require_once("../../WA_CMS/WA_CMS.php"); ?>
immediately after the opening <head> tag which is causing me the problem.
As an aside, I there a reason this line is in the head section and not before the <!doctype html> ??