FindChangeByList script

I'm trying to use this pre-made script in CS4, and I customized the accompanying .txt file with all our Find-and Replace needs, but when I actually try to the run the script on a document, the following error message comes up:

Error Number: 23

Error String: does not have a value

File: [name and location of jsx file follows]

Line: 159

Source: app.doScript(myString, ScriptLanguage.javascript);

Anyone know how to get past this? It's very hard to see what Line 159 in the script file has to do with anything.

Thanks.