failed to open stream: No such file or directory

bom dia, subi uma aplicação php para o hostinger da forma indicada no curso, consigo abrir um formulario que só faz um post e não tem codigo php, quando faço o post vou para a pagina que adiciona no banco de dados, o que eu recebo de resposta são os seguintes erros:

Warning: include(connect-to-mysql.php): failed to open stream: No such file or directory in /home/u914665096/public_html/DevMakerTest/DAOcontacts.php on line 2

Warning: include(): Failed opening 'connect-to-mysql.php' for inclusion (include_path='.:/opt/php-5.5/pear') in /home/u914665096/public_html/DevMakerTest/DAOcontacts.php on line 2

Warning: include(connect-to-mysql.php): failed to open stream: No such file or directory in /home/u914665096/public_html/DevMakerTest/Add-contact.php on line 3

Warning: include(): Failed opening 'connect-to-mysql.php' for inclusion (include_path='.:/opt/php-5.5/pear') in /home/u914665096/public_html/DevMakerTest/Add-contact.php on line 3

Warning: mysqli_query() expects parameter 1 to be mysqli, null given in /home/u914665096/public_html/DevMakerTest/DAOcontacts.php on line 6

Warning: mysqli_error() expects parameter 1 to be mysqli, null given in /home/u914665096/public_html/DevMakerTest/Add-contact.php on line 14 falha ao adicionar contato teste. erro:

Warning: mysqli_close() expects parameter 1 to be mysqli, null given in /home/u914665096/public_html/DevMakerTest/Add-contact.php on line 19

codigo da pagina que retorna o erro:

include("DAOcontacts.php");
include("connect-to-mysql.php");

include("head.php");

$name = $_POST["name"];
$telephone = $_POST["telephone"];
$email = $_POST["email"];

if(addContact($connection, $name, $telephone, $email)){?>
    <p Class ="alert-success"> contato <?=$name?> adcionado com sucesso! </p><?php
}else{
    $ErrorMsg=mysqli_error($connection);
?>
<p Class = "alert-danger"> falha ao adicionar contato <?=$name?>. erro:<?=$ErrorMsg?></p>
<?php 
}
mysqli_close($connection);
?>

conecta com o banco de dados:

<?php
$connection = mysqli_connect('mysql.hostinger.com.br','u914665096_dev','devdev','u914665096_dev');

codigo do DAO:

<?php
include("connect-to-mysql.php");

function addContact($connection, $name, $telephone, $email){
    $query = "insert into contacts (name, telephone, email) values ('{$name}','{$telephone}','{$email}')";
    return mysqli_query($connection, $query);   
}

function getContacts($connection){
    $query = "select * from contacts";
    $contacts = array();
    $result = mysqli_query($connection, $query);
    while($contact=mysqli_fetch_assoc($result)){
        array_push($contacts,$contact);
    }
    return $contacts;
}

acredito que seja um problrma com os includes, não consigo resolver, alguma luz? :D