SQL & PL/SQL

Have a Foxpro frontend, insert into an Oracle table. Datatypes different: Foxpro = logical,
ORACLE = numeric. Wrote trigger to do datatype conversion:

CREATE OR REPLACE TRIGGER trig1 BEFORE INSERT ON table1
FOR EACH ROW
BEGIN
SELECT TO_NUMBER(col1) INTO :new.col1 FROM dual;
END;

For some reason I am getting error message that identifier coll1 must be declared. Why can't it see this column? Can anyone tell me?
Thanks