多文件上传Codeigniter问题

Question

我在尝试上传多张图片时不断获得You have not selected a file to upload：

// Needs PartID from main part insert
$PartImageName = $this->input->post('PartImageName'); 
$PartImageAlt = $this->input->post('PartImageAlt');
$PartImageMain = $this->input->post('PartImageMain');
$PartImage = $this->input->post('PartImage');
for($i = 0; $i < count($PartImageName); ++$i){
    // Need to upload and resize the image(s)...make sure they are image(s), and are less than 5M in size
    //$PartImage[$i] is the file
    $fconfig['upload_path'] = PART_IMAGE_PATH;
    $fconfig['allowed_types'] = 'gif|jpg|png|bmp';
    $fconfig['max_size']    = '51200000000';
    $fconfig['remove_spaces'] = TRUE;
    $this->upload->initialize($fconfig);
    // upload the initial image:
    $this->upload->do_upload('PartImage[]');
    var_dump($fconfig);
    var_dump($this->upload->display_errors());
    $upload_data = $this->upload->data(); 
    $file_name = $upload_data['file_name'];
    // now resize it:
    $rconfig['image_library'] = 'gd2';
    $rconfig['source_image'] = PART_IMAGE_PATH . $file_name;
    $rconfig['maintain_ratio'] = TRUE;
    $rconfig['width'] = 640;
    $rconfig['height'] = 480;
    $this->image_lib->initialize($rconfig);
    $this->image_lib->resize();
    var_dump($rconfig);
    var_dump($this->image_lib->display_errors());
    $this->image_lib->clear();
    // now create a thumbnail
    $tconfig['image_library'] = 'gd2';
    $tconfig['source_image'] = PART_IMAGE_PATH . $file_name;
    $tconfig['new_image'] = PART_IMAGE_THUMB_PATH . $file_name;
    $tconfig['maintain_ratio'] = FALSE;
    $tconfig['width'] = 194;
    $tconfig['height'] = 146;
    $this->image_lib->initialize($tconfig);
    $this->image_lib->resize();
    var_dump($tconfig);
    var_dump($this->image_lib->display_errors());
    $this->image_lib->clear();
    $data = array('partImageName'=>$PartImageName[$i],
                  'partImageAlt'=>$PartImageAlt[$i],
                  'partImageMain'=>(isset($PartImageMain[$i])) ? $PartImageMain[$i] : 0,
                  'partImage'=>$file_name,
                  'partID'=>$PartID,);
    $this->db->insert('TblPartOptionImages', $data);
}

我做错了什么，我该如何解决？

文件字段为：<input type="file" id="PartImage" name="PartImage[]" />

我已验证文件路径是世界可写的