codeIgniter 上传图片失败

我是 codeIgniter 的新手，我正在尝试进行注册表单，上传个人资料图片并将图像名称存储在数据库中。所以当我使用form_open它存储在数据库上时就好了但文件没有进入我的目录，当我使用form_open_multipart图像上传但查询设置为空并且所有操作都失败时。

<?php
class User extends CI_Controller{

    public function __construct()
    {
    parent::__construct();
        $this->load->helper('url_helper');
        $this->load->model('user_model');
        $this->load->helper('form');
        $this->load->helper('date');
        $this->load->library('form_validation');        
    }

    public function sign_up(){
        $this->form_validation->set_rules('name', 'Username', 'trim|required|min_length[3]|max_length[20]');
        $data['title']='Sign Up Page'; 
        $config = array(

            array(
            'field'=>'email',
            'label'=>'Email',
            'rules'=>'required'
                    ), 
            array(
            'field'=>'mobile',
            'label'=>'Mobile',
            'rules'=>'required'
                    ), 
             array(
            'field'=>'flat_number',
            'label'=>'flat number',
            'rules'=>'required'
                    ),
             array(
            'field'=>'street_number',
            'label'=>'street number',
            'rules'=>'required'
                    ),
             array(
            'field'=>'street',
            'label'=>'street',
            'rules'=>'required'
                    ),
            array(
            'field'=>'area',
            'label'=>'area',
            'rules'=>'required'
                    ),
             array(
            'field'=>'governor',
            'label'=>'governor',
            'rules'=>'required'
                    ),
             array(
            'field'=>'name',
            'label'=>'Name',
            'rules'=>'required'
                    ),
             array(
            'field'=>'birth_day',
            'label'=>'birth day',
            'rules'=>'required'
                    ),
             array(
            'field'=>'birth_month',
            'label'=>'birth month',
            'rules'=>'required'
                    ),
             array(
            'field'=>'birth_year',
            'label'=>'birth year',
            'rules'=>'required'
                    ),
             array(
            'field'=>'gender',
            'label'=>'gender',
            'rules'=>'required'
                    ),
             array(
            'field'=>'user_type',
            'label'=>'user type',
            'rules'=>'required'
                    ),
            );
        $this->form_validation->set_rules($config);
        $this->form_validation->set_rules('password', 'Password', 'required');
        $this->form_validation->set_rules('password_comfirm', 'Password Confirmation', 'required|matches[password]');
        $config['upload_path']          = './uploads/';
        $config['allowed_types']        = 'gif|jpg|png';
        $config['max_size']             = 1000;
        $config['max_width']            = 1024;
        $config['max_height']           = 1024;
        $this->load->library('upload', $config);
        $this->upload->do_upload('profile_pic');
        if($this->form_validation->run() === false){

             $this->load->view('user/sign_up',$data);
        }
        else{
             $data = array('upload_data' => $this->upload->data());

            $this->user_model->add_user();
            $this->load->view('main_pages/succes');
        }

    }

}

<?php

类 User_model 扩展了 CI_Model{

public function __construct(){
    $this->load->database();
}

public function add_user(){
    $datestring = '%d-%m-%Y';
    $time = time();
    $sign_up_date = mdate($datestring, $time);
    $address = $this->input->post('flat_number').'-'.$this->input->post('street_number').'-'.$this->input->post('street').'-'.$this->input->post('area');
    $birthdate = $this->input->post('birth_day').'-'.$this->input->post('birth_month').'-'.$this->input->post('birth_year');
        $data = array(
            'name'         => $this->input->post('name'),
            'sign_up_date' => $sign_up_date,
            'email'        => $this->input->post('email'),
            'mobile'       => $this->input->post('mobile'),
            'address'      => $address,
            'password'     => $this->input->post('password'),
            'birthdate'    => $birthdate,
            'gender'       => $this->input->post('gender'),
            'user_type'    => $this->input->post('user_type'),
            'pic_name'     => $this->input->post('profile_pic'),
            'governor'     => $this->input->post('governor')
        );
    return $this->db->insert('user',$data);
}

}