I got a PFX file with a private key (it was imported from another Windows installation and the button "Export Private Keys" was pressed). I installed it, and got the message that the import was succeful. When I see them in certmgr, I see the message
A system level error occurred while verifying trust
And no valid private key with a certificate.
Also this certificate has the "This certificate has an invalid digital signature." status.
What is a possible reason?