Before installing it, I checked my previous version 10 to make sure all was OK, then I went ahead with the new installation.
The installation failed - with a error message suggesting I did not have the previous version on my system, then aborted. I returned to V.10 to check it again, and found that this too does not now work! I believe that I have had this probem on earlier downloaded upgrades. It is such a time waster!
My system is Windows 7 64bit.
I explained all this to tech. support who replied with, "You must have the previous version installed". Not much help, but I'll keep trying.