i had an install problem w/Melodyne 4 that lasted a couple months or so because Celemony's tech support was TERRIBLE. i could not install Melodyne 4 w/o installation errors; Sonar would not see Melodyne 4 vst3 even though it was in the right place. after much toiling, i decided to try something that defied normal logic (mine, at least) and it fixed the problem. after uninstalling Melodyne & cleaning the registry, i started the install process again, but this time, when i was given the choices of which components to install, i UNCHECKED the VST2 component so that that would not install. the VST3 component then installed correctly & Melodyne became available to me as a Region Effect. much rejoicing!