According to the JCR 2.0 spec:
18.104.22.168 Root Version
The version graph always contains at least the root version. This is a null version that stores no state and simply serves as the eventual predecessor of all subsequent versions. Its frozen node does not contain any state information about the versionable other than the node type and identifier information found in the properties jcr:frozenPrimaryType, jcr:frozenMixinTypes, and jcr:frozenUuid.
so you should not be using the root version & expecting to retrieve information out of it.