Mail Rules window says "No Scripts Installed" next to "Run AppleScript"
I'm trying to create a rule in Mail that will run an AppleScript. But when I choose "Run AppleScript" in the action section of the rule-creation window, the dropdown to the right says "No Scripts Installed".
If I click on that dropdown, it has one option: "Open in Finder". When I choose that, a Finder window opens to the folder Library/Application Scripts/com.apple.mail/. I dropped my AppleScript file into that folder, but when I tried again to make a rule, I still got the "No Scripts Installed" dropdown.
I'm running Mail version 6.3 in OS X 10.8.3.
Any idea how to get this working properly? Thanks.