You have attempted to publish a property of type Real, which is not allowed. Published floating point properties must be Single, Double, or Extended.

program Produce;
  type
    Base = class
      R : Real48;
    published
      property RVal : Real read R write R;
    end;
end.

The published Real48 property in the program above must be either removed, moved to an unpublished section or changed into an acceptable type.

program Produce;
  type
    Base = class
      R : Single;
    published
      property RVal : Single read R write R;
    end;
end.

This solution changed the property into a real type that will actually produce run-time type information.