Ok, i found out what was the problem that made any attempt with Quickcreds fail !
inside the folder tree i had:
/tools/Responder instead of /tools/responder/ ,
and even if changing the payload.txt to point at /tools/Responder/ the code somehow was failing.
Decide then to rename /tools/Responder with /tools/responder without any modify of payload and voila ! the code was completed without any errors.
Thanks to Altecheon to let me run that test and let me think once more again on it
i dont know why even if modify the payload and point Responder instead of responder wasnt working but at least now is working so it's all good !!
/cheers