Mysql foreign key Error

Hej alle på udvikleren.

Jeg sidder og og prøver at oprette en DB i Mysql, men kan ikke tilføje en foreign key til min table.

Her er hele min code til oprettelse af tabeller.

 /* Create database */
 CREATE DATABASE Payz;
 USE Payz;
 
 /* Create customer table */
 CREATE TABLE users (
     id int NOT NULL AUTO_INCREMENT,
     companyName varchar(300) NOT NULL,
     cvr int NOT NULL,
     legalBusinessName varchar(300) NOT NULL,
     address varchar(250) NOT NULL,
     zipcode int NOT NULL,
     city varchar(250) NOT NULL,
     phone int NOT NULL,
     contactName varchar(250) NOT NULL,
     contactMail varchar(250) NOT NULL,
     contactPhone int NOT NULL,
     bank varchar(250) NOT NULL,
     regNo int NOT NULL,
     accountNo int NOT NULL,
     companyLogo varchar(4000) NOT NULL,
     approved bit NOT NULL DEFAULT FALSE,
     PRIMARY KEY(id),
     KEY idx_cvr(cvr)
 ) CHARACTER SET utf8 ENGINE=InnoDB;
 
 /* Create admin table */
 CREATE TABLE admins (
     id int NOT NULL AUTO_INCREMENT,
     username varchar(250) NOT NULL,
     password varchar(250) NOT NULL,
     email varchar(250) NOT NULL,
     PRIMARY KEY(id),
     KEY idx_email(email)
 ) CHARACTER SET utf8 ENGINE=InnoDB;
 
 /* Create payment table */
 CREATE TABLE payment (
     id INT  NOT NULL AUTO_INCREMENT,
     paymentOwner int unsigned NOT NULL,
     referenceNo INT NOT NULL,
     referenceText varchar(4000),
     amountToPay int NOT NULL,
     recipientEmail varchar(250) NOT NULL,
     creationDate date NOT NULL,
     paymentMade bit NOT NULL DEFAULT FALSE,
     paymentMadeOn date NULL,
     PRIMARY KEY(id)
 ) CHARACTER SET utf8 ENGINE=InnoDB;
 
 
 /* Create payment table update event(TRIGGER)*/
 CREATE TRIGGER event_insert BEFORE INSERT ON payment FOR EACH ROW SET NEW.creationDate = NOW();
 
 
 /* Alter payment table, add constraint */
 ALTER TABLE payment ADD 
     CONSTRAINT FK_payment
     FOREIGN KEY (paymentOwner) REFERENCES users(cvr)
     ON UPDATE CASCADE
     ON DELETE CASCADE

Det eneste der ikke virker denne del

 /* Alter payment table, add constraint */
 ALTER TABLE payment ADD 
     CONSTRAINT FK_payment
     FOREIGN KEY (paymentOwner) REFERENCES users(cvr)
     ON UPDATE CASCADE
     ON DELETE CASCADE

Når jeg prøver at køre det, får jeg følgende fejl.

Error Code: 1005
Can't create table 'payz.#sql-658_5020' (errno: 150)

Jeg har prøvet at kigge på mysql.com(http://dev.mysql.com/doc/refman/5.0/en/innodb-error-codes.html)

Men der er ikke meget hjælp at hente ud over "table creation failed because a foreign key constraint was not correctly formed"

Håber der er nogle her inde som måske kan se hvad jeg gør galt.