电子邮件检查错误和成功注册

Question

else{
    $reg = '/^[_a-z0-9-]+(\.[_a-z0-9-]+)*@[a-z0-9-]+(\.[a-z0-9-]+)*(\.[a-z]{2,3})$/';  

 if(preg_match($reg,$User_Email))
 {


    $addUserSQL=
        "insert into
    Users (userType,userFName, userSName, userAddress, userPostcode, userTelNo, userEmail, userPassword)
    values ('C','".$User_FName."', '".$User_SName."','".$User_Address."','".$User_Postcode."', '".$User_telNo."', '".$User_Email."', '".$User_Password."')";
    $exeaddUserSQL=mysql_query($addUserSQL);



   if(mysql_errno($conn) == 0 ){
        echo "<p>You've successfully registered";
        echo "<p>To continue, please <a href=login.php>login</a></p>";

    }
    else{
        echo "<p>You've not successfully registered</p>";
        if (mysql_errno($conn) == 1062){
    echo "<p>Email already taken</p>";
    echo "<p>Go back to <a href=register.php>register page</a></p>";
        }
    }   
}
else{
    "<p>Email not in the right format</p>";
}
}

这部分代码没有运行，我无法弄清楚为什么它允许我注册但不会在p标签中发出消息。我试图将括号放在正确的位置，但它仍然没有工作

<?php echo $login->get_link_logout(); ?>