Aperture shows information about a certificate in way of a banner across the top of a certificate in Aperture. Among other alerts this contains a section for Unapproved Issuer banner.
This shows us that the this certificate under management that have been issued by an Unapproved CA. This article describes how to configure Approved CAs.
The Approved CAs are configured in WebAdmin. The setting can be found under Settings > Certificate tab on the root of Policy tree. You will select which root or intermediate certificate should be listed as an "Approved" issuer. You will be making this selection out of the available roots in the Roots Tree. If your intermediate or root certificates are not in the selection, you can add them by going to the roots tree and click "Add"