So then I bought a new Hauppauge USB TV Tuner for my new (used) Dell Win10 box.
Then I recently upgraded to PD 18.
Unfortunately, PD 18 still does not work with my Tuner.
Same error message as before. (Something like PD cannot communicate with the tuner.)
So I don't think it's my fault anymore.
(I suppose I should write up a Support Ticket.)