anchor.diff:                State, lists:keyreplace(WatchedPid, 1, RemPids, NewEntry))
       end.
   
  --spec state_del_watched_pid(state(), comm:mypid()) -> state().
  -state_del_watched_pid(State, WatchedPid) ->
  +-spec state_del_watched_pid(state(), comm:mypid(), comm:mypid()) -> state().
  +state_del_watched_pid(State, WatchedPid, Subscriber) ->
       %% del watched pid remotely, if not longer necessary
       RemPids = state_get_rem_pids(State),
       case lists:keyfind(WatchedPid, 1, RemPids) of
  -        false -> log:log(error, "req. to delete non watched pid~n"),
  +        false -> log:log(warn,
  +                         "req. from ~p (~p) to delete non watched pid ~p.~n",
  +                        [Subscriber, pid_groups:group_and_name_of(Subscriber),
  +                         WatchedPid]),
                    State;
           Entry ->
               TmpEntry = rempid_dec(Entry),
  
positive.code:     {Changed, S1} = state_del_entry(State, {Subscriber, WatchedPid, Cookie}),
      %% delete watched pid remotely, if no longer needed
      case Changed of
          deleted -> _S2 = state_del_watched_pid(S1, WatchedPid);
          unchanged -> S1
      end;
  
  
negative.code:     %% entry time is still unmodified since this message was triggered
      RemPids = state_get_rem_pids(State),
      case lists:keyfind(WatchedPid, 1, RemPids) of
          false -> log:log(warn, "req. to delete non watched pid ~p.~n",
                           [WatchedPid]),
                   State;
          Entry ->
              NewRemPids =
  