Does WEKA only work for specific PMML versions?

I would like to use WEKA to score a model I've been given in PMML version 4.2. I'm trying to test out WEKA, just making a single PMMLFactory.getPMMLModel call, and when I use my PMML file I get this exception:
weka.core.UnassignedClassException: Class index is negative (not set)!

I've found some sample PMML files online and my code is able to read them with no exceptions. These are versions 3.2 and 4.1, so I am wondering if WEKA does not support PMML version 4.2? I have not found other 4.2 files to test with.

Thanks!