Due to Weka 3.7.13 completely overhauling its expression parsers, the multi-search package no longer worked with that version of Weka. Furthermore, I got a bug report that the meta-classifier couldn’t be used within the Experimenter. The Experimenter was outputting the models before anything was built and ran into a NullPointerException.
Therefore, I made a new release available today: 2015.10.15