template loader render to string not working

I just want to get one entire xml page content into another xml file so i come up with this code. but using render_to_string , i am getting the value but nothing printed.

from django.template.loader import render_to_string
def createxml(request):
    template_vars = {}

    rendered = render_to_string('messageheaderxmlmain.xml')

    #For messageheader 
    template_vars['somevalue'] = rendered
    t = loader.get_template('xmlforgoogle/somename.xml')
    c = Context(template_vars)

    return HttpResponse(t.render(c), content_type = "application/xhtml+xml")

This is my xml file

<?xml version="1.0" encoding="UTF-8"?>
{{ rendered }}

what i am missing ..?