Did you append the intermediate cert from the ca before importing it back to the CSS?
Here are the steps in which I use to gen the rsa key, send to CA for signing , validating and importing.
Gen the RSA key and associate it to a filename
Gen the csr then send to signing authority
once received concatonate the signed cert with the CA intermediate.
import file, associate cert to filename and use the ssl verify command to ensure key and cert match.