where did you get the owout and owin commands? for PBP+ ive used the oread and owrite. ive been playing with the serial only buttons and the RTC button. using the owrite command followed by the memory access as specified by dallas (its on one of their PDF datasheets on iButton standards) and have managed to get the full access for the serial buttons. by the sound of it you are challenging the key with the wrong access code. the results i get for no button are FF (hex) which is 255 -max value, and when the key was inserted wrong or the port was shorted to ground then i got 0, i also got the same answers if i asked the wrong or received the wrong request code.
one problem i have with the RTC iButton is its in binary and having to try and devide by the correct digit. which is quite amusing so far.....