Enable debugging! The only way to be able to track down the cause of these kind of issues. I added an environment variable JAVA_OPTIONS with this value: "-Dssl.debug=true -Dweblogic.StdoutDebugEnabled=true -Djavax.net.debug=all"
Also, in WLS I enabled debugging for these topics: ->Environment->Servers->AdminServer: tab ‘Debug’: - Default: DebugSSL - Weblogic, node 'Security': certpath, certrevocchecking, credmap, keystore and ssl
You will still need to do a lot of digging, but at least the error-messages are there!