Here's a quick description. You start the Wall Tool, you decide to switch to another Ribbon for some reason, then decide to return to the Wall tool. You see the Wall tool right there on the Home tab and click to start the Wall tool again. You don't notice that the Wall Tool is already selected and you also don't notice that the Place Wall Ribbon tab is active. Nothing happens, or at least it sure looks like nothing happens. Happened to you? Just need to remember to scan the Ribbon for active tabs.
(The audio sounds a little "buzzier" than it sounded when I first listened to it. Maybe my ears were shot after a full day. I'll replace it when I have a different environment to record in.)