CodeIgniter form submission does not include a value for a hidden field [duplicate]

I have two tables named services and payment and two forms for inserting values in to it. When I enter data into services, I am getting two field names id and customer_id and I want to convert those values into payment table while adding to the corresponding id. This is my services table.

id  code     customer_id    particulars     serialno    complaint   
22  ORD00022    16             tv             100         ddfds     
23  ORD00023    19             GH             565          gfdg     
24  ORD00024    15             tv             122         sdfsd     
25  ORD00025    16             cvbcv           5         tgtdfgfg   
26  ORD00026    16             cvbcv           5         tgtdfgfg 

This is my payment table

id      order_id    customer_id   actual_amount   paid_amount   balance     type
3          0            0              250.00       100.00       150.00     Cash
4          0            0              250.00       50.00        100.00     Cash
5          0            0              150.00       50.00        100.00     Credit
10         0            0              500.00       500.00       400.00     Credit
13         26           16             250.00       100.00       0.00       Cash

This my view page

<li> <a href="" class="make_payment" data-toggle="modal" data-target=".payment" id="<?php echo $row->id; ?>" customer-id="<?php echo $row->customer_id; ?>" >Make Payment</a> </li>
<div class="modal payment">
<div class="modal-dialog">
 <form action="<?php echo base_url(); ?>account_control/make_payment"   method="post" id="assign-form">
<div class="modal-content">
<div class="modal-header">
  <button type="button" class="close" data-dismiss="modal" aria-label="Close"><span aria-hidden="true">&times;</span></button>
  <h4 class="modal-title">Make Payment</h4>
</div>
<div class="modal-body">
 <div class="box-body">
  <div class="form-group">
    <label for="inputEmail3" class="col-sm-2 control-label">Total Amount</label>

    <div class="col-sm-10">
      <input type="text" class="form-control" name="total_amount" id="total_amount" placeholder="Total Amount">
    </div>
    <div class="clearfix"></div> 
  </div>
  <div class="form-group">
    <label for="inputEmail3" class="col-sm-2 control-label">Paid Amount</label>

    <div class="col-sm-10">
      <input type="text" class="form-control" name="paid_amount" id="paid_amount" placeholder="Paid Amount">
    </div>
    <div class="clearfix"></div>
  </div> 
  <div class="form-group">
    <label for="inputEmail3" class="col-sm-2 control-label">Balance</label>

    <div class="col-sm-10">
      <input type="text" class="form-control" name="balance" id="balance" placeholder="Balance">
    </div>
    <div class="clearfix"></div> 
  </div>
  <div class="form-group">
    <label for="inputEmail3" class="col-sm-2 control-label">Balance</label>
    <div class="col-sm-10">
      <select name="type" class="form-control">
        <option value="Cash">Cash</option>
        <option value="Credit">Credit</option>
      </select>
    </div>
    <div class="clearfix"></div> 
  </div>
  <input type="hidden" name="order_id" id="order_id">
  <input type="hidden" name="customer_id" id="customer_id">        
</div>


<div class="modal-footer">
  <button type="button" class="btn btn-default" data-dismiss="modal">Close</button>
  <input type="submit" class="btn btn-primary" value="Pay">
</div>

My controller looks like this..

public function make_payment()
{
    $status = $this->Account_model->make_payment();
    if ($status) {
        $this->session->set_flashdata('message', 'Payment successful');
    } else {
        $this->session->set_flashdata('message', 'Payment Failed');
    }
    redirect('account_control/view_order');
}

My model looks like this

public function make_payment()
{  
    $paid = $this->input->post('paid_amount');
    $total = $this->input->post('total_amount');
    $balance = $this->input->post('balance');
    $customer_id = $this->input->post('customer_id');
    $order_id = $this->input->post('order_id');

    $data = array(
        'order_id' => $order_id,
        'customer_id' => $customer_id,
        'actual_amount' => $total,
        'paid_amount' => $paid,
        'balance' => $balance
    );

    if ($this->db->insert('payment', $data)) {
        return TRUE;
    } else {
        return FALSE;
    }
}

I am getting an error like this

Error Number: 1048

Column 'order_id' cannot be null

INSERT INTO `payment` (`order_id`, `customer_id`, `actual_amount`,      `paid_amount`, `balance`) VALUES (NULL, 'NULL', '100', '50', '50')

Filename: C:/wamp64/www/account/application/models/Account_model.php

Line Number: 196

This is my output view from the makep payment below action displays the modal

 S.No    Order #          Date   Particulars   Serial/IME No  Complaints    Action
  1       ORD00027   06/07/2016    led            11          sedsdf       make payment

  2       ORD00026   06/13/2016    cvbcv           5          tgtdfgfg     make payment

the last row i inserted in the payment table is the value i assumed that i should have to get