Fabricio,

F> Very interesting!!!!!! Is not a Firebird thing!!!!
F> MSSQL have the same behavior.

FWIW I'm not surprised. I would be if nulls could slip past a
"a2.valor_t2 = :Val and a2.pos_t2 = :Pos" where clause on any decent
DBMS.

Ciao
--
Nando Dessena
http://www.flamerobin.org