CodeIgniter: When form data inserted to a table through an array, only "0" values are written in to the database

Everything is working fine except, instead of writing the data on the form, it writes zeros. The table (new_reservation) looks like this after submitting some values:

PK: res_id (AI, NN)

Not Null: All except "ext_bed"

Model: (reservations_model.php)

class Reservations_model extends CI_Model {

function add_reservations($data) {
    $this->db->insert('new_reservation', $data);
    return;
}

}

Controller: (reservations.php)

class Reservations extends CI_Controller {

function index() {
    $this->load->view('/main/new_reservation');
    $this->load->model('reservations_model');
}

function add_reservations() {       
    $data = array (
    'room_type' => $this->input->post('room_type'),
    'meal_type' => $this->input->post('meal_type'),
    'bed_type' => $this->input->post('bed_type'),
    'ext_beds' => $this->input->post('ext_beds'),
    'number_of_guests' => $this->input->post('number_of_guests'),
    'start_date' => $this->input->post('start_date'),
    'end_date' => $this->input->post('end_date'),
    'reservation_duration' => $this->input->post('reservation_duration'),
    'room_number' => $this->input->post('room_number'),
    'total' => $this->input->post('total')
    );
$this->reservations_model->add_reservations($data);
$this->index();
}
}

View: (new_reservation.php in /views/main folder)

<?php echo form_open('reservations/add_reservations'); ?>

<p>      
<label for="room_type">Room Type*: </label>
<select id="room_type"></select>
</p>

<p>      
<label for="meal_type">Meal Type*: </label>
<select size="1" multiple="multiple" id="meal_type"></select>
</p>

<p>      
<label for="bed_type">Bed Type*: </label>
<select id="bed_type"></select>
</p>

<p>      
<label for="ext_beds">Extra Bed(s): </label>
<input type="text" id="ext_beds" />
</p>

<p>      
<label for="number_of_guests">Number of Guests: </label>
<input type="text" id="number_of_guests" />
</p>

<p>      
<label for="start_date">Check-in Date*: </label>
<input  type="text" id="start_date" />
</p>

<p>      
<label for="end_date">Checkout Date*: </label>
<input type="text" id="end_date" />
</p>

<p>      
<label for="reservation_duration">Duration: </label>
<input type="text" id="reservation_duration" />(Nights)
</p>

<p>      
<label for="room_number">Room Number: </label>
<input type="text" id="room_number" />
</p>

<p>      
<label for="total">Total: </label>
<input type="text" disabled="disabled" id="total" readonly="readonly" />
</p>   

<p>
<input class="btn" type="reset" />
<input class="btn btn-primary" type="submit" value="Check-in" />
</p>

<?php echo form_close(); ?>