Help: problem in file uploading

Code:

function upload_photo()

    {

        $data['mod'] = strtolower(get_class($this));

        $data['role'] = $this->session->userdata('data_id');    

        $dt = $this->session->userdata('user_id');

        $data['user'] = $this->main->getProfile($dt)->row();

        $data['error'] = '';

        

        $config['upload_path'] = './img/pics/';

        $config['allowed_types'] = 'gif|jpg|jpeg|png';

        $config['max_size']    = '100';

        $config['max_width']  = '1024';

        $config['max_height']  = '768';

        

        $this->load->library('upload', $config);

               

        if($this->form_validation->run('update')===FALSE)

        {

            $this->form_validation->set_error_delimiters('<p class="error">', '</p>');

        }

        else

        {

            if ( ! $this->upload->do_upload())

            {           

                $data['error'] = $this->upload->display_errors('<p class="error">','</p>');

            }    

            else

            {

                $data2 = array('upload_data' => $this->upload->data());              

                $file_data = $this->upload->data();

                $file_name = $file_data['file_name'];

                

                $detail = array(

                        'image_path' =>$file_name

                        

                    ); 

                    echo $file_name;

                $this->main->save($detail, $dt);

                //redirect('student_profile/update');

            }

        }  

        

        $data['content'] = $this->load->view('panes/upload_pic', $data, TRUE);

        $this->output->enable_profiler(TRUE);

        $this->load->vars($data);

        $this->load->view('template');        

    }

Code:

function save($data, $item)

    {

        if ($item=='')

            {

            $this->db->trans_start();

            $this->db->insert('users', $data);

            $item = $this->db->insert_id();

                if($data['data_id']==1)

                {

                    $this->save_detail($item);

                }

            $this->db->trans_complete();                     

            }

        else

            {

            $this->db->trans_start();

            $this->db->where('a.user_id', $item);

            $this->db->update('users spms_a', $data);

            $this->update_detail($item);    

            $this->db->trans_complete();

            }

            

        return $item;    

    }

Code:

<div class="contentpane">

    <div class="guestBookcontainer" style="padding-left:10px; ">

    <div class="sectortitle" style="padding-left:8px">Upload Profile Picture</div>&nbsp;

       <p class="response">&nbsp;</p>

       <div style="padding-left:30px">

       

            &lt;form method="post" action="&lt;?=base_url();?&gt;student_profile/upload_photo" enctype="multipart/form-data" &gt;&nbsp;

                <div class="rleft">Picture</div>

                    &lt;input type="file" name="userfile" /&gt;&lt;?php echo $error;?&gt;                                                                                                    

                    &lt;input type="submit" value="Save" name="submit"&gt;    

                

            &lt;/form&gt;

      </div>



    </div>

</div>