Do tabulky se mi zapíše jen první uživatel a dál už žádný

CREATE TABLE `uzivatele` (
   `id` INT NOT NULL AUTO_INCREMENT PRIMARY KEY ,
   `username` VARCHAR( 32 ) NOT NULL ,
   `password` VARCHAR( 32 ) NOT NULL ,
   `mail` VARCHAR( 64 ) NOT NULL ,
    UNIQUE (`username`)
) ENGINE = innodb CHARACTER SET cp1250 COLLATE cp1250_czech_cs

<?php
$con =  mysqli_connect("","","","")

if(IsSet($_GET['j'] AND $_GET['p'] AND $_GET['m'])){
$jmeno = $_GET['j'];
$md5pass = $_GET['p'];
$mail = $_GET['m'];


$prepare = $con->prepare("INSERT INTO `uzivatele`(`username`,`password`,`mail`) VALUES (?,?,?)");
$prepare->bind_param("sss", $jmeno, $md5pass, $mail);
$prepare->execute();
$con->close();

header("");
}

else{
header("");
}
?>

mysql_connect ("", "", "");
        mysql_select_db ("");
        
        mysql_query("insert into uzivatele (username, password, mail) values ('$jmeno', '$md5pass', '$mail')");

        header("");