Thanks for that. Yes definitely a Text instance variable, just double checked. I'll check your sample and post back if and when I work out what I've done wrong. BTW as a test I changed the evaluation to use <> instead of = and *all* instances were picked.
Edit: Ok looking closer at your sample, I noticed that you don't have quotes around your text in the initial values. To me it was intuitive to use quotes as it's a string, but anyway! Thanks for helping me see this.
Edit 2: And also I had a redundant 'pick by evaluate' condition instead of a simple Compare Instance Variable condition.