input post empty

Hi guys,
i'm writing a backend in CI (frontend separated in html/js)
when i tried to send POST data to my controller $_POST is empty..
I've tried for few way but i always receive a empty array.
Maybe the problem could be about htaccess???

tried to call my API 

Code:

http://mysite.com/users/register_post_user

two vars
id=test
email=[email protected]
tried already to set url with or without  / at the end    

my controller - Users.php -

PHP Code:

public function register_post_user()
    {
        print_r($_POST);

                //few alternative i tried
        //echo $_POST['id']." ".$_POST['email'];  
        //$id = $this->input->post('id');
        //$email = $this->input->post('email');
        //echo $id." ".$email;
    } 


in that case the result is

Code:

Array ( )

i'm sending request by Postman and my frontend. the result doesn't change.
here my - .htacces - (modified only for removing index.php)

Code:

RewriteEngine on
RewriteCond $1 !^(index\.php|resources|robots\.txt)
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule ^(.*)$ index.php/$1 [L,QSA]