It's not a bug but documented change in SQL behavior.

>

>CREATE CURSOR cTest ( D1 D,Suma N(14,2))
>FOR asd = 1 TO 15
>    INSERT INTO cTest VALUES (DATE()+asd,asd)
>NEXT
>
>SET ENGINEBEHAVIOR 70 && Corect results
>SELECT SUM(SUMA) AS Suma FROM cTest WHERE D1 BETWEEN {^2005/12/1} AND {^2005/12/3} into CURSOR rrr
>? _tally  && Expected 0, prints 0, empty file
>
>SET ENGINEBEHAVIOR 80 && Corect results
>SELECT SUM(SUMA) AS Suma FROM cTest WHERE D1 BETWEEN {^2005/12/1} AND {^2005/12/3} into CURSOR rrr
>? _tally  && Expected 0, prints 0, empty file
>
>
>SET ENGINEBEHAVIOR 90 && Incorect results
>SELECT SUM(SUMA) AS Suma FROM cTest WHERE D1 BETWEEN {^2005/12/1} AND {^2005/12/3} into CURSOR rrr
>? _tally  && Expected 0, printed 1, Suma field contains NULL
>

>
>Maybe Fabio already find this bug, but I didn't remember to see it.