If you use the Get New… functionality to get any effects that apply to window opening, closing, minimizing, maximizing, full screen, etc, then after being downloaded, they will not actually appear in the KCM. Instead they will only appear in the Animations KCM. The effects only appearing there is logical in general, but it's made awkward by the fact that the place where you download them and the place where they appear are different. It makes you wonder if the download failed or something.