How can I get this code to work? It's in mysql, I keep getting an error 1822' failed to add foreign key constraint. Missing index for constraint'

CREATE TABLE EMPLOYEE ( employeeNumber VARCHAR (15) NOT NULL, employeeName VARCHAR (20) NOT NULL, department VARCHAR (10) NOT NULL, phone INT NOT NULL, PRIMARY KEY (employeeName, department) CREATE TABLE DEPARTMENTS( department VARCHAR (10) NOT NULL, department Code VARCHAR(10) NOT NULL, department Name VARCHAR(30) NOT NULL, FOREIGN KEY (department) REFERENCES EMPLOYEE (department) CREATE TABLE EMAIL_INFO( employee Name VARCHAR (20) NOT NULL, email VARCHAR (30) NOT NULL, FOREIGN KEY (employeeName) REFERENCES EMPLOYEE (employeeName) );