Help with Outlook for Mac 2011 Applescript

Hi there, I am trying to create a custom signature using Applescripts. I have the following code:

tell application "Microsoft Outlook"

make new signature with properties {name:"test1", content:"<html>test</html>"}

end tell

However, when I run this code I get the following error:

error "The variable signature is not defined." number -2753 from "signature"

Please help.

Thanks!

~KumarND