jQuery Grid Plugin - jqGrid

I can export grid settings no problem. But I am having real difficulty loading up a new grid with the saved settings. This is with both xml and json.

Going back to basics and using the demonstration page as an example I tried this:

jQuery(document).ready(function(){
    jQuery("#test1").jqGridImport({imptype:"xml",impurl:"testxml.xml"});
});

Using the sample XML file under New in version 3.4, Import Configuration from XML http://trirand.com/jqgrid/testxml.xml

This works fine.

But if I change the code to this:

[code]jQuery(document).ready(function(){
    jQuery("#test1").jqGridImport({imptype:"xml",impurl:"testxml.php"});
});[/code]

and change the testxml.xml file to testxml.php with the file contents changed to:

[code]<?php

<?php
echo '<?xml version="1.0" encoding="UTF-8"?>
<roots>
    <grid>

--- snipped ---

</rows>
</roots>';
?>[/code]

There is no grid displayed and no errors in firebug at all.