Quark Find String Weirdness

OK. This is killing me. I can’t for the life of me figure out why this isn’t working.

Script A below works. Script B doesn’t. The only difference is that, in Script A, the string I’m looking for in the docuement is hard coded into the “if exists” line.

In Script B, it’s a variable that picks up user input from a dialog. Anybody have any ideas why B won’t work. I’m using Quark 6.0 on a Mac running OS 10.3.7.Thanks.

-------SCRIPT A---------
tell application “QuarkXPress Passport”
activate
tell document 1
if exists (text of every story where it is “soup”) then
display dialog “IT WORKED!”
end if
end tell
end tell

-------SCRIPT B---------
display dialog “Enter search string:” default answer “”
set the search_string to the text returned of the result

tell application “QuarkXPress Passport”
activate
tell document 1
if exists (text of every story where it is search_string) then
display dialog “IT WORKED!”
end if
end tell
end tell