Gagal upload image

Halo, saya mau bertanya bagaimana cara agar upload gambar tidak gagal dengan menggunakan CI. Saya sudah mencoba var_dump pada display error nya dan hasilnya adalah upload path tidak valid, padahal saya sudah cek dan memastikan path yg dimasukkan sudah benar. Berikut saya sertakan kode dari controller submit

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');
class Weeklysurvey extends CI_Controller
{

	# CONSTRUCT
	function __construct()
	{
		parent::__construct();
		$this->load->model('weekly_survey_model');
		$this->load->helper('asset_helper');
		$this->load->library('uploader');
		$this->no_cache();
	}

	# CLEAR CACHE
	protected function no_cache()
	{
		header('Cache-Control: no-store, no-cache, must-revalidate');
		header('Cache-Control: post-check=0, pre-check=0',false);
		header('Pragma: no-cache');
	}

	function weekly_survey_input()
	{
		if($this->input->post('go_submit'))
		{

			#upload image
			$config['upload_path'] = './uploads/surveyreport/';
			$config['allowed_types'] = 'gif|jpg|png';
			$config['max_size']	= '100';
			$config['max_width']  = '1024';
			$config['max_height']  = '768';

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

			if (!$this->upload->do_upload('upload1'))
			{
				$error = $this->upload->display_errors();
				//var_dump($this->upload->display_errors());

			} else {
				$result = $this->upload->data();
			}

			#display form
			$this->load->view('weekly_survey_input',$data);
		}
		else{
			$this->load->view('weekly_survey_input',$data);
		}
	}

}

?>

berikut adalah viewnya :

<div class="row">
            <div class="col-md-12" style="background-color:#fff;padding-top:20px;padding-bottom:20px;">
				<form method="post" action="<?php echo base_url()."surveyreport/weeklysurvey/weekly_survey_input.html"; ?>" enctype="multipart/form-data">
					<div class="row">
						<div class="col-md-12" class="form_group03" style="display:inline-block;margin-bottom:30px;">
							<div class ="col-md-6" class="image_dokumentasi">
								<div class="col-md-12">
									<h3 class="title02">Dokumentasi</h3>
								</div>
								<div>
									<input name="upload1" type="file" class="form-control">
								</div>
							</div><!--end of image_dokumentasi-->

						</div>
						<div class="col-md-12" style="display:inline-block;margin-bottom:5px;margin-top:50px;text-align:center;">
							<input type="submit" value="Simpan" name="go_submit" class="btn btn-success">
						</div>
					</div>
				</form>
			</div><!-- END COL-MD-12 -->
		</div>