[Scala on Android] NoSuchMethodException excepiton

Hi list -
I have a jar with following two objects, having no difference functional.
They work fine and have the same behaver on "normal" platform.
But when I dx them to android platform (using the cool sbt plugin - https://github.com/jberkel/android-plugin), the first one failed, throwing NoSuchMethodException.
proguard has not deleted the methods, since I put them both in "-keep" arg.
Any advice?
Thanks a lot.


object Helper {
  implicit def helpersWrap[A](obj: A) = new {
    def applyTo[B](f: A => B) = {
      f(obj)
    }
  }
}

object Helper2 {
  class Wrapped[A](val obj:A){
    def applyTo[B](f: A => B) = {
      f(obj)
    }
  }
  implicit def helpersWrap[A](obj: A) = new Wrapped(obj)
}