Why I cannot insert data into database - php

Question

<?php
session_start();
$host = "localhost";
$user = "root";
$password = "";
$database = "tuition";
$conn = mysqli_connect($host, $user, $password, $database);
?>
<div role="tabpanel" class="tab-pane fade in" id="sign_up">
<form action="" method="post">
<input type="text" class="form-control" name="register_name" placeholder="Name" required />
<input type="text" class="form-control" name="register_ic" placeholder="IC" required />
<input type="telephone" class="form-control" name="register_phone" placeholder="Telephone" required />
<input type="email" class="form-control" name="register_email" placeholder="Email" required />
<input type="password" class="form-control" name="register_password" placeholder="Password" required />
<input type="submit" class="form-control" name="register_btn" value="Sign up" />
</form>
</div>
<?php
if(isset($_POST['register_btn'])){
$name = $_POST['register_name'];
$ic = $_POST['register_ic'];
$phone = $_POST['register_phone'];
$email = $_POST['register_email'];
$password = md5($_POST['register_password']);
$result = mysqli_query($conn,"select parent.parent_ic from parent where parent_ic ='$ic'");
if(mysqli_num_rows($result)!=1){
mysqli_query($conn,"insert into parent(parent_name,parent_ic,parent_email,parent_contact_num,parent_password) values ('$name','$ic','$email','$phone','$password')");
?>
<script type="text/javascript">
alert("success");
</script>
<?php
}
else{
?>
<script type="text/javascript">
alert("fail");
</script>
<?php
}
}
?>
It coming out with alert success, but it do not insert the data into the database.But when I hard code insert the data into the database it work! Why?
Here is the result after I click submit button:

Answer 1

You should see by printing error after insert data query
echo("Error description: " . mysqli_error($conn));
I think your MySQL error will be there.