RT, and the "priority" flag in Outlook?

Ok, as a simple test, I made a custom template for correspondence named Correspondence High Priority:

RT-Attach-Message: yes
X-Priority: 1 (Highest)
X-MSMail-Priority: High

{$Transaction->Content()}

Basically, I copied the “Correspondence” template and added the 2 X-priority lines.
I added a custom scrip to my test queue to use the above template on correspondence:

On Correspond Notify AdminCCs Correspondence High Priority

However, it doesn’t set the flag. When I view the headers, I don’t see the 2 lines at all. It’s as if RT is stripping them off or not including them.
I do know the 2 lines will work to set the flag though, because I tested this outside of RT by constructing an email with the 2 lines-- and it worked.

If I have other default scrips, such as “On Correspond Notify AdminCCs Correspondence”, could that be taking priority and ignoring my custom scrip?

Here are the relevant headers I received from the above test, which do not include the missing desired header lines:Subject: [rt.foo.com #4142] test of priority
From: “root via RT” testing@foo.com
Reply-To: testing@foo.com
In-Reply-To: 20120815161345.AA31115053D@rt.foo.com