-* File backcolor.fex
-SET &OUTPUT=EXL2K;
TABLE FILE CAR
SUM SALES
BY COUNTRY
BY CAR
ON TABLE PCHOLD FORMAT &OUTPUT
ON TABLE SET STYLE *
TYPE=REPORT, OBJECT=STATUS-AREA,PAGE-LOCATION=OFF,$
TYPE=REPORT, GRID=ON, BORDER=LIGHT,$
TYPE=DATA,
     COLUMN=SALES,
     BACKCOLOR=RGB(123 175 55),
     WHEN=SALES GT 30000,
$
TYPE=DATA,
     COLUMN=SALES,
     BACKCOLOR=RGB(204 51 0),
     WHEN=SALES GT 0,
$
END

This what you get:
XL output

However if you change the output to AHTML, you get:
AHTML output

To remedy, you have to change the order of the WHEN attributes!

Thanks Daniel for sharing,Is the execution hierarchy is different in AHTML compared to others?