accepting a digitally signed certificate

I have an Excel Template that I am trying to accept the certificate and trust
the publisher. I seem to be able to do this fine on my XP machines, but my
Vista machines are not seeming to recognize it.

I have Trust the Publisher and it asks me to accept the certificate, which I
do, and it says that it has impoted successfully; however, when I view the
Trusted Publishers list, the name is not there (in fact there are none) and I
continue to have difficulties operating the template fully...some of the
programming is not working.

Is there a step I am missing in accepting certificates/trusting publishers
in Vista?

Thanks