Project 2010 VBA - Editing a Filter to Add a Field

I am writing a VBA module for Project 2010. In that module I am trying to edit an existing filter by adding another field name to check. Here's what I wrote:

FilterEdit Name:="Company", TaskFilter:=True, Create:=False, OverwriteExisting:=False, Parenthesis:=True, _
                FieldName:="% Complete", Test:="does not equal", Value:=100, ShowInMenu:=False, ShowSummaryTasks:=True

The "Company" filter already checks a field I call Company.

Currently I get a run-time error 1004 saying that I do not have a valid field name. I assumed that it doesn't like the '%' character, but it doesn't seem to like any field name no matter what I enter, like "Finish".  

1) Is this the way to edit a filter to add another field to check?

2) Why is it complaining about an invalid field name if that column exists?