FK validate data but in select join tables parent and child don't search data

CREATE TABLE parent (

  `cod_cta` VARCHAR(30) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '',

  `des_cta` VARCHAR(100),

   PRIMARY KEY (`cod_neg`,`cod_cta`),

) ENGINE=INNODB;

CREATE TABLE child (

  `cod_asi` INT(11) NOT NULL DEFAULT 0,

  `num_lin` INT(11) NOT NULL DEFAULT 0,

  `cod_cta` VARCHAR(30) CHARACTER SET utf8 COLLATE utf8_unicode_ci NOT NULL DEFAULT '',

  PRIMARY KEY (`cod_asi`,`num_lin`),

  CONSTRAINT `fk_child_cta` FOREIGN KEY (`cod_cta`) REFERENCES parent ( `cod_cta`) ENGINE=INNODB;