What is the exact error message you are getting? 

I would check Version on VISTA, if you have Sage company open, go to Help, about Sage 50, it shows your version (from 2016.0 to 2016.3)

You can also open Sample on Win 10, and go to help and about Sage to verify the version as well.  Most like they are not they same

(from CD you are mostly on 2016.0) 

once you verify your version, you can go to your VISTA machine 

C:\Users\Public\Documents\Sage Software\Simply Accounting\Download

and copy the i.e. SA_20162CPUP1.exe (2016.2) SA_20163CPUP1.exe (2016.3)  and install on Win 10 computer.

once your version match, it should open backup no issue

hope this helps

Thanks Jason.  The issue got resolved just before I went to try this.  I was not involved but I believe your solution would have worked and i am told it was an issue with the versions. My only question is how the two computers ended up with different versions when they both were installed from the same disc.  Possibly when i installed on new computer it went out and got an update which rendered it incompatible with version on Vista, and no one had bothered to update that version.

Thanks ever so much for taking the time to  respond to my question and trying to help.

You are welcome Sagacity, good to heard you have resolved the issue.

Sage provides product and payroll update in Dec and June, so Vista computer must have downloaded and installed them at the time, where Windows 10 is new install, since 2016 it is not supported so it won't have automatically download and installed them. (so you have to do it manually)