How to Insert Multipe checkbox in cakephp?

i will create insert multiple checkbox, but i dont understand the syntax, i am googling but i dont know. what is wrong? can anyone help me?

i will create checkbox for form add suspect

<tr>
    <td valign="top">KWH</td>
    <td valign="top">&nbsp;&nbsp; : &nbsp;&nbsp;</td>
    <td><input type="checkbox" name="data[PlnPostpaidSuspect][kwh]" value="RI/450 VA"> RI/450 VA &nbsp;&nbsp;&nbsp;
        <input type="checkbox" name="data[PlnPostpaidSuspect][kwh]" value="RI/900 VA"> RI/900 VA &nbsp;&nbsp;&nbsp;
        <input type="checkbox" name="data[PlnPostpaidSuspect][kwh]" value="RI/1300 VA"> RI/1300 VA <br/>
        <input type="checkbox" name="data[PlnPostpaidSuspect][kwh]" value="RI/2200 VA"> RI/2200 VA &nbsp;
        <input type="checkbox" name="data[PlnPostpaidSuspect][kwh]" value="RI/3600 VA"> RI/3600 VA &nbsp;
        <input type="checkbox" name="data[PlnPostpaidSuspect][kwh]" value="RI/6600 VA"> RI/6600 VA <br/></td>                   
</tr>

in the controller

public function add() {
    $this->loadModel('Product');
    $this->loadModel('User');
    if (!empty($this->request->data)) {
        $suspect = $this->PlnPostpaidSuspect->save($this->request->data);       

        if (!empty($suspect)) {
            $this->loadModel('Mutation');
            $this->loadModel('Transaction');    
            $this->request->data['Mutation']['inbox_id'] = $this->request->data['PlnPostpaidSuspect']['inbox_id'];
            $this->request->data['Transaction']['inbox_id'] = $this->request->data['PlnPostpaidSuspect']['inbox_id'];
            $this->request->data['Mutation']['user_id'] = $this->request->data['Transaction']['user_id'];


            $this->Mutation->save($this->request->data);
            $this->Transaction->save($this->request->data);

            $this->Session->setFlash(__('The pln postpaid suspect has been saved'), 'flash/success');
            $this->redirect(array('action' => 'index'));

        }else{

            $this->Session->setFlash(__('The pln postpaid suspect could not be saved'), 'flash/error');

        }
    }

    $products = $this->Product->find('list');
    $users = $this->User->find('list',array(
            'fields'=>array('User.id','User.username'),
            'order'=>array('User.username')                
            )
    );
    $this->set(compact('products','users'));
}