flyer, we need screenshots. From what you've said I assume everything is done correctly, so I think you might've done some mistakes while setting stuff up.
Your game is Diamond/Pearl, yes?
DPPt tend to fluctuate sometimes, so instead of turning the game on the last beep, restart you DS, turn the game on ASAP and soft reset on the last beep. It doesn't change anything but you might find that method easier/more efficient than the one you're currently using (I find soft resetting easier, for example).
Just checked and latest PPRNG is definitely compatibile with IV Gen. Also, if you have HGSS, try that first, as it's easier to RNG.