php mysql写登陆注册的网页，验证用户输入的密码和数据库中保存的密码是否一致时的问题。

代码是：
<?php
$Username=$_POST['Username'];
$Password=$_POST['Password'];
$con=mysqli_connect("127.0.0.1","root","19930126liujia","my_db");
if(mysqli_connect_errno())
{
echo "Failed to connect to MySQL: " . mysqli_connect_error();
}

$result=mysqli_query($con,"SELECT * FROM Users WHERE Username='$Username'");
if($row=mysqli_fetch_array($result))
{
if($Password == $row['Password'])
echo "Congratulations!Login is successful!";
else
{
echo "Sorry!The password you entered is incorrect!<br>";
echo "<br/>";
echo "Please click here to try again:";
exit("<a href='http://127.0.0.1/Login.html'>Relogin</a>");
}
}
?>
为什么即使输入的密码是正确的还是显示登录失败！求大神解。。。

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