Getting NoSuchMethodError when using Actor

Hello.

I use OneJAR to bundle my Scala-Swing application together with some
libraries, including scala-library.jar into one jar file.
The application itself runs fine until a class that implements Actor is
used. I get this error:

Exception in thread "AWT-EventQueue-0" java.lang.NoSuchMethodError:
scala.actors.ReactorCanReply$class.$init$(Lscala/actors/ReactorCanReply;)V
at de.mabe.taillogger.TailLogger$Tailor.(TailLogger.scala:40)
at de.mabe.taillogger.TailLogger.createTailor(TailLogger.scala:33)
at de.mabe.taillogger.TailLogger.startTailor(TailLogger.scala:25)
at
de.mabe.xea.ui.frame.TailLoggerFrame.startLogUpdating(TailLoggerFrame.scala:42)
...

I found some threads regarding this exception but I'm not sure whether they
apply for my case.
Any ideas how I could solve this?

Manfred