PHP include variable file problem, Im confused!

Hi All
Am trying to include a template file in my theme, but the file name is a variable set at the back end (this works I can get the file name to echo properly)

Im having problems getting the file to include in the index page. So far I have this:

<?php include bloginfo(‘template_directory’); ?>/thatfolder/<?php echo $test_test;?>`

with $test_test as the file name im after. Rather than pulling in the contents of the file it just echos the location, so I get:

http://localhost:8888/wptestsitedata/wp-content/themes/mytheme/thatfolder/FILENAME.php

With the variable FILENAME being correctly echoed.

I really want to include the contents of this file, but cant seem to make a simple include work with a variable.

Can anyone help?? Thanks if you can!!!