well the only thing I see weird is you said you have 4 pokemon in your party, but wanted to advance 5 frames. walking 128 steps with 4 pokemon in your party is gonna advance it 4 frames bringing you to frame 5 not 6...
alternatively, how many times did you hit seeds when calibrating(finding your DS paramateres) you should do this at least 5 times.
people usually have 2 Timer0 values that could come up, maybe the first time you did it, you got your less common timer0 value, but ussually you get a different one, this would cause problems hitting the seed.
other than that, maybe the IVs you got from PO were wrong, but just so happened to match the IVs of a seed on a similar time... this is... very unlikely, but could happen theoretically. PO isn't a very exact science.