Take every grid, and connect it with a DB, just for test.
Then in the event onHeader put the next:
?>
<h1>TEST</h1>
<?php
if you execute the application, and use the QUIKSEARCH you will see: (like image attached)
Why and how can repair it.
This is just a example, but i need insert HTML code in onHeader event, and all time show me the square like error.
Thank you