Hi Andy - great article, as ever. I can't see that I didn't follow your instructions to the letter but during the Mixing Constraint and Expression Evaluation Operations section I couldn't even close the Precedence Constraint Editor window. This is because @MyBool is set to false (and a positive condition will never be met). Subsequently I couldn't execute the package, for obvious reasons. Any reason why it worked for you, but not for me?

Thanks,

Richard