So I used to work for a firm where we used a bit of software from a small firm and the developer (who also owned the firm) was coming in to see if there was any features he could add or minor bugs that needed fixing based on our usage. I sat with a group of fellow tech staff and went over the properties of a function that he thought we wanted including and at the end of this said that shouldn't be a problem to add that. Slightly stunned we said the feature is already there and went on to explain what we wanted to be able to do is modify it to include parameter X when running. That as it turned out was no problem and then we turned to something else a feature that we wanted including but was at the moment sadly lacking. "Ah" he says "You just don't know how to do that I'll show you" and then spent 15 mins trying to get his software to do something it wouldn't.
Nice bloke but he had completely forgotten that they hadn't released the next version that did a lot of what we wanted. It apparently was in alpha testing and he was sure we'd been sent a copy which we hadn't.