The activity delegate with Handler '{0}' cannot be referenced by activity '{1}' because the latter is not in the implementation ...

The activity delegate with Handler '{0}' cannot be referenced by activity '{1}' because the latter is not in the implementation of activity '{2}'.  An activity delegate can only be referenced by the implementation of an activity which specifies that activity delegate as a child or import.  The activity delegate with Handler '{0}' is declared by activity '{3}'.