Option to use different 'single' template for some posts

Hey Folks

I have a custom posts type (its reviews) and I would like them to use an alternative single.php template. But i don’t see the template drop down at all in that section.
I have deactivated/re-activated the theme, still no go.

this is the top of my new single-review.php file:

<?php
/*
Template Name: Review Template
*/

How can i select which template these posts will use?

thanks!