"on process text" stopped working -- how can I figure out why?

[Bryan]

For some reason, my "on process text" applescripts running through QS
have suddenly stopped working. Has anyone else had this problem? Any
ideas about how I can figure out what's going on?

Here's the problem in more detail. I've got a script called
MyScript.scpt saved in my Quicksilver actions. When the content of the
script is the following, it doesn't work.

using terms from application "Quicksilver"
        on process text mytext
                show large type mytext
        end process text
end using terms from

That is, I invoke Quicksilver, hit period, type "foobar," hit tab,
start typing MyScript, hit enter. Nothing happens. However, if I
change the script content to the following, it works fine.

using terms from application "Quicksilver"
        set _text to "foobar"
        show large type _text
end using terms from

Then I invoke Quicksilver, type MyScript and tab to run it. I do get
"foobar" in large type. Any ideas? How can I figure out what's going
wrong?

OS X Lion 10.7.3.
Quicksilver ß65 (3920)