Error when using html in grid onheader event

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

test.png

Check this:

[ATTACH=JSON]{“data-align”:“none”,“data-size”:“medium”,“data-attachmentid”:89756}[/ATTACH]

test.png

Thank you man.

All ok