NULL result in MySQL querrie.

[admin]

I made following table,

create table myProjectRole (
myProjectRoleID smallint unsigned primary key auto_increment not null,
fkEmployeeID smallint unsigned not null REFERENCES Employee,
ProjectRoleStart date,
ProjectRoleEstimatedEnd date,
ProjectRoleEnd date,
ProjectRoleBooking float(1,2));

INSERT INTO myProjectRole VALUES ('','1',?999-09-23??999-11-30??,?5?;
INSERT INTO myProjectRole VALUES ('','1',?999-10-23??001-11-30??,?5?;
INSERT INTO myProjectRole VALUES ('','1',?000-09-23??,?002-03-23??5?;
INSERT INTO myProjectRole VALUES ('','1',?001-09-23??003-11-30??,?0?;
INSERT INTO myProjectRole VALUES ('','1',?001-09-23??,?002-03-23??5?;
INSERT INTO myProjectRole VALUES ('','1',?002-05-23? ? ,?003-11-30??0?;

I want to go in day by day and check Booking but as soon as I start using date functions in my where querries I get NULL as a result. What am I doing wrong?

SELECT sum(ProjectRoleBooking) as Booking
FROM myProjectRole
WHERE fkEmployeeID='1';

gives the result 170.

SELECT sum(ProjectRoleBooking) as Booking
FROM myProjectRole
WHERE to_days(2001-08-27)>=to_days(ProjectRoleStart)
AND to_days(2001-08-27)<= to_days(ProjectRoleEnd)
AND fkEmployeeID='1'
AND DAYOFWEEK(2001-08-27)<7
AND DAYOFWEEK(2001-08-27)>1;

gives the result NULL.