Hi Silvio,
first of all Orca3D is a 32bit application (as Rhino v4), and installs normally under Rhino v4 /32 in Windows 7 /64 (I have it on my PC).
By any chance, do you have both Rhino v5 WIP / and Rhino /v installed on the same PC ? This might confuse the installer
I would like to see this error, maybe we can web conference tomorrow morning before 10 - I speak italian ?
In the mean time, please try launching the installation as administrator (right click on the installer file, then select
run as administator).
If the installation succeeds, the next time you run Rhino please also run it as administator. This is needed to start the Orca3D license service.
nick danese
+33 4 9291 1324
ndar@ndar.com