Problem with "required fields" in PHP

programming
1

I have a HTML page with a e-mail form (which is connected to a PHP file). I want to put some message for “required fields” in the forms but it’s not working. This is the .php file and no matter what it always shows “You need to fill some fields” even if those 3 fields are filled:

 
 
<?php
if ((!$n_empresa_field) || (!$ciudad_field) || (!$email_field))
{ 
	Print "You need to fill some fields"; 
} else { 
 
$to = "metatron@mymail.com"; 
$subject = "Cotización..."; 
$headers = 'From: metatron@mymail.com';
$n_empresa_field = $_POST['n_empresa'];
$direccion_field = $_POST['direccion'];
$colonia_field = $_POST['colonia']; 
$cp_field = $_POST['cpostal'];
$dropdown = $_POST['pais'];
$dropdown2 = $_POST['estado'];
$ciudad_field = $_POST['ciudad']; 
$telefono_field = $_POST['telefono'];
$n_solicitante = $_POST['n_individuo'];
$email_field = $_POST['email'];
$message = $_POST['message']; 
foreach($_POST['check'] as $valor) { 
$check_msg.= "$valor
"; 
} 
$body = "Nombre Empresa: $n_empresa_field
 Dirección: $direccion_field
 Colonia: $colonia_field
 Código Postal: $cp_field
 País: $dropdown
 Estado: $dropdown2
 Ciudad: $ciudad_field
 Teléfono: $telefono_field
 Nombre del que solicita la información: $n_individuo
 Email: $email_field
 Servicios que necesita:
 $check_msg
 Comentarios:
 $message"; 
 
echo 'Thankyou. You can close the window.'; 
mail($to, $subject, $body, $headers); 
}
?>