I suggest you:

go to your xara/magix account and deactivate the computer you are trying to install it on

uninstall XDPX [and reboot computer]

reinstall and, all being well, it should install ok up to the v12 you are licenced for [edit - ie update as well]

I had a lot of trouble with this myself - the program locked me out

I think it was because it had not been deactivated prior to reinstall the first time I tried it... but I have no confirmation of that.. it took a couple of trys to get it right

if it does not work then back to xara support....