Foreign Keys usage???

[it99ama]

I'm trying to make a foreign key relation between two tables but it doesn't seem to work!
#-------------------------------------
CREATE TABLE operation (
operationID int(11) NOT NULL AUTO_INCREMENT,
name varchar(50) default NULL,
PRIMARY KEY (OperationID)
);

#---
CREATE TABLE agent (
agentID int(11) NOT NULL AUTO_INCREMENT,
name varchar(50) default NULL,
operationID int(11) default NULL,
PRIMARY KEY (agentID),
FOREIGN KEY (operationID) REFERENCES operation (operationID)
);
#----------------------------------------------------

Then when i do an insert like:
INSERT INTO operation VALUES(1,'Newbiemission');
INSERT INTO agent VALUES(' ','Newbie',2);

This should cause an error!?? But it doesn't!
The number '2' inserted into the 'agent' table should cause an error because of the FK!!

What am I doing wrong?

/Andy