Thanks Brian.

The only thing I can think of is that BS thinks Plague Stone has less than 50% Placing, but I ran your placeFifty calc and it selected all 4 horses. Not sure how you can tell how they're ranked from that?

Here's my Calc, System And results, which put Plague Stone out of order. Why? I can't work it out.

That's really just a curiosity I suppose. If you can't see a way around the artificial separation, I'm just flogging a dead horse.
Thank you again for taking the time to look at it.

Regards,

Steve

The Calc:
MyPts(PPRANK,1,NUMSTR,NUMSTR,1,0)
The System
0.CALCNAME=Poll
DAYCODE$"7"
LOCATION$"S"
Within(RNO,5,5)
The result:
25/08/2018 (SAT) ROSEHILL (ROS) WIN PLC QN EX TT FF
SR 5 # 1 1L0x Performer 5.00 3RD 2.00
SR 5 # 2 381x Paquirri 7.00
SR 5 # 3 110x Jonker 6.00 4TH
SR 5 # 4 x111 Dio D'Oro 8.00
SR 5 # 5 5x14 Plague Stone 2.00
SR 5 # 6 11x Graff 9.00 WON 5.20 1.80
SR 5 # 7 310x Tchaikovsky 4.00
SR 5 # 8 1x4x Neutrality 3.00 2ND 1.70
SR 5 # 9 60x5 Ringerdingding 1.00 12.0