AppleScript Not Deleting Email from Server

I wrote an AppleScript to move certain email to the trash. Moving them to trash works fine, but the emails don't get removed from the server. I have the account set to removed them immediately and all other emails not processed by my AppleScript get removed. I'm thinking I need to add some additional code to the script to get that done. Any idea what that would be?

Here's the pertinent code:

Code:

set theAccount to account of mailbox of this_message
set mailbox of this_message to mailbox "Trash" of theAccount

The script exits afterwards