When setting this up you should either use the 'include new file' option or craft the message body by clicking on the DW icon. Which option did you choose? If you create the page yourself you will need to add the binding for your memo field to the message page.
Once you have configured the message body check on the trigger that is being used. It should be based on the submit button from the form being pressed.
As a test of UE you could just add it to a new page and not use any variables, just fill it in with static values. Then run the page to test out the email and see if it is sent.