HTC's Sense 3.0 Destined Only for Newer Hardware
HTC has confirmed via one of its official Twitter accounts that its new Sense 3.0 user interface overlay will not be made available to devices that are already in the market. It will debut on the EVO 3D, Sensation 4G, and View 3D (Flyer) tablet, but will not work on older HTC phones.
i always replaced it with Launcher Pro.
have you tried Launcher Pro?