Win 10 64 bit registery files

I have installed several Win 10 64bit versions up to 2.74
When I click on an epub file it does not open and Calibre does not show in the open with dialog box until
I scroll down to search for other apps and click on the Calibre .exe file nothing happens and the file does not open.
There were no entries in the registery for Calibre.
I used another computer where Calibre operated properly, so I exported the Calibre registery files and the merged them with the computer that it did not work on, and it still would not open the files when clicked on, or Calibre was clicked on from the open with box.
I uninstalled and reinstalled 5 times and it still will not open files.
Itwill open epub files when I pick the open file dialog from the main Calibre program.
Any suggestions would help