Upon installing our valid Thawte SSL for securelogin.mycompanay.net I came across twice an error.
1. Certificate CA "CN=Thawte SSL CA, O="Thawte, Inc.", C=US" must be added and enabled in Certificate Trust List
This error was solved very quick by activating it in the Certificate Trust List.
2.Certificate CA "EMAILADDRESS=premium-server@thawte.com, CN=Thawte Premium Server CA, OU=Certification Services Division, O=Thawte Consulting cc, L=Cape Town, ST=Western Cape, C=ZA" must be added and enabled in Certificate Trust List
This error caused my a bit of a headache. There is a Thawte Premium Certificate installed though but any time I attempted to import the SSL certificate ClearPass prompted above error. It turned out that the pre-installed Thawte Premium Root Certificate is faulty.
At the end I removed all pre installed Thawte Root Certificates and reinstalled them by downloading them from Thawte.com
Perhaps the post is of help for those who may encounters the same problem.