title: ORA-02270 error
body: <p>I tried to create a table with a foreign key to another one but I don't know why this error </p>
  
  <blockquote>
    <p>ORA-02270: no matching unique or primary key for this column-list</p>
  </blockquote>
  
  <p>keeps popping up every time I try, please help me</p>
  
  <pre><code>CREATE TABLE usuarios(
      username VARCHAR2(100),
      cedula VARCHAR2(100),
      ultimoAcceso DATE,
      CONSTRAINT Pk PRIMARY KEY (cedula,username)
      ) ;
  
  CREATE TABLE pagoPlanillas(
      ced VARCHAR2(100),
      fecha DATE,
      detalle VARCHAR2(100),
      salario VARCHAR2(100),
      CONSTRAINT FK1 FOREIGN KEY(ced) REFERENCES usuarios(cedula)
      ) ;
  </code></pre>