Hi Kungtum, The Serial Number you have attempted to register has already been registered by another Planet Auran member. All Serial Numbers are unique and only licensed for use on one machine at a time, therefore each Serial Number can only be registered by one Planet Auran profile. Possible reasons: You may be running more then one Planet Auran profile. You can not transfer your serial number between your profiles, so you will need to use the profile where your serial number is registered. If you have forgotten the details of the profile where you serial number is registered, please use the 'Forgotten your password?' links on the Planet Auran login page. You may have purchased a second hand copy of this software. Our license indicates, the software is not transferable so unfortunately, we can not provide support in this circumstance. If this isn't the case, we suggest that you return your product to the place of purchase and ask for a replacement, as they may have sold you a previously returned product. Regards, Auran www.auran.com