In v7, you can use the Loop action for that.
http://www.kinook.com/VisBuildPro/Manual/loopaction.htm
What is probably happening is that the script expression is also getting evaluated by the Watches pane, so another option might be to clear out that pane or remove [Step] and [LastStep] from it.
http://www.kinook.com/VisBuildPro/Ma...atchespane.htm