Security Certificate Outlook 2016

Just installed Outlook 2016 through Office 365 and am trying to install a security certificate for my
e-mail through the trust center. When I try to choose a certificate (.pfx) file it says no certificate is available, even though I received a certificate from Comodo and installed it. I does not see the certificate.
I am not sure how regedit may help but there are some directions out there but not for Outlook 2016. Any
buddy got any ideas it would be helpful.

No none of these causes are mention, I receive a Red X with "A error occurred while trying to import the security information"

Yes I could use it outside of Outlook but prefer the extra layer of security. Outlook allows the user to
disable a certificate and block unwanted certificates.

There must have been a issue with the link they sent me and I asked that it be resent and now have the Comodo Certificate working in Outlook. Thanks for the help anyway.