"META Sample 07_EvolutionaryParameterOptimization fails"

Hi,

when I try to run 07_EvolutionaryParameterOptimization.xml from samle/07_Meta in
RapidMiner 4.2 (download version), RapidMiner fails with the error message:
"Process failed!

java.lang.NullPointerException
    at com.rapidminer.operator.visualization.ProcessLogOperator.fetchAllValues(ProcessLogOperator.java:217)
    at com.rapidminer.operator.visualization.ProcessLogOperator.apply(ProcessLogOperator.java:184)
    at com.rapidminer.operator.Operator.apply(Operator.java:664)
    at com.rapidminer.operator.meta.ParameterOptimizationOperator.getPerformance(ParameterOptimizationOperator.java:65)
    at com.rapidminer.operator.meta.EvolutionaryParameterOptimizationOperator.setParametersAndEvaluate(EvolutionaryParameterOptimizationOperator.java:277)
    at com.rapidminer.operator.meta.ESParameterOptimization.evaluateIndividual(ESParameterOptimization.java:60)
    at com.rapidminer.tools.math.optimization.ec.es.ESOptimization.evaluate(ESOptimization.java:386)
    at com.rapidminer.tools.math.optimization.ec.es.ESOptimization.optimize(ESOptimization.java:328)
    at com.rapidminer.operator.meta.EvolutionaryParameterOptimizationOperator.apply(EvolutionaryParameterOptimizationOperator.java:201)
    at com.rapidminer.operator.Operator.apply(Operator.java:664)
    at com.rapidminer.operator.OperatorChain.apply(OperatorChain.java:377)
    at com.rapidminer.operator.Operator.apply(Operator.java:664)
    at com.rapidminer.Process.run(Process.java:612)
    at com.rapidminer.Process.run(Process.java:582)
    at com.rapidminer.Process.run(Process.java:572)
    at com.rapidminer.gui.ProcessThread.run(ProcessThread.java:61)

Is this just a problem of my local copy or a general bug in the sample?

Regards,
Chris