Problem in rapidminer execution

nav

Hi, today running rapidminer from my java code in a linux environmet I got this error:

2011-09-30 12:43:16 WARNING: Cannot load operator class: java.lang.NoClassDefFoundError: Could not initialize class com.rapidminer.operator.performance.ForecastingPerformanceEvaluator (OperatorService.parseOperators())
  java.lang.NoClassDefFoundError: Could not initialize class com.rapidminer.operator.performance.ForecastingPerformanceEvaluator
      java.lang.Class.forName0(Native Method)
      java.lang.Class.forName(Class.java:247)
      com.rapidminer.operator.OperatorDescription.<init>(OperatorDescription.java:89)
      com.rapidminer.tools.OperatorService.parseOperators(OperatorService.java:282)
      com.rapidminer.tools.OperatorService.parseOperators(OperatorService.java:279)
      com.rapidminer.tools.OperatorService.parseOperators(OperatorService.java:279)
      com.rapidminer.tools.OperatorService.parseOperators(OperatorService.java:279)
      com.rapidminer.tools.OperatorService.parseOperators(OperatorService.java:279)
      com.rapidminer.tools.OperatorService.parseOperators(OperatorService.java:255)
      com.rapidminer.tools.OperatorService.registerOperators(OperatorService.java:229)
      com.rapidminer.tools.plugin.Plugin.registerOperators(Plugin.java:464)
      com.rapidminer.tools.plugin.Plugin.registerAllPluginOperators(Plugin.java:670)
      com.rapidminer.tools.OperatorService.init(OperatorService.java:188)
      com.rapidminer.RapidMiner.init(RapidMiner.java:413)
      TCPClustering.Clustering.doClustering(Clustering.java:269)
      TCPClustering.ClusteringMainClass.main(ClusteringMainClass.java:93)

Do you know what is the problem and how can I solve it? thanks

nav

I answer myself. To solve the problem I removed the hidden directory .RapidMiner5 and then I lunched again RapidMiner, which made again the directory and after that running my java program the problem doesn't appear.