Here is my itinerary as I planned it:

GRU JNB 6/4/07
JNB DAR 6/6/07
DAR JNB 6/10/07
JNB SIN 6/16/07
SIN BKK 8/10/07
BKK RGN 8/11/07
RGN BKK 8/13/07
BKK MNL 8/22/07
MNL SIN 8/28/07
SIN PVG 8/28/07
PVG ICN 9/2/07
ICN NRT 9/7/07
NRT LAX 9/10/07
LAX SNA 9/10/07
SNA BOS 9/15/07
BOS GRU 12/16/07

The rates desk is telling me that I need to buy a separate ticket between DAR -JNB and RGN-BKK because I'm in JNB and BKK one too many times. But I thought I could use those two cities as layovers twice and stop over once and still be OK. Can someone please point out what it is I'm missing?

Thanks.
David