Export data dengan phpexcel selalu object of class stdclass could not be converted to string

Hallo semua, saya newbie ! Saya punya koding seperti ini:

$dataArray = [];

		$header = $this->getHeader($schedule_id);
		$discs 	= DB::table('interview_test_disc_answer')
			->where('id_interview_schedules', $schedule_id)
			->select('sort','ops_a', 'ops_b', 'ops_c', 'ops_d')
			->orderby('sort', 'ASC')
			->whereNull('deleted_at');

		$dataArray[] = ['No', 'Col A', 'Col B', 'Col C', 'Col D'];
		$dataArray[] = $discs->get()->toArray();

		//foreach($discs as $row){
		//	$dataArray[] = $row->toArray();
		//}
		//var_dump($dataArray);

		Excel::create('disc-applications', function($excel) use ($dataArray, $header){

            $excel->setTitle('Disc Applications');
            $excel->setCreator('Recruit')->setCompany($this->companyName);
            $excel->setDescription('disc-applications file');

            $excel->sheet('sheet1', function ($sheet) use ($dataArray, $header) {
            	$sheet->setCellValue('A1', 'Title');
            	$sheet->setCellValue('B1', 'Disc Applications');
            	$sheet->setCellValue('A2', 'Name');
            	$sheet->setCellValue('B2', $header->full_name);
            	$sheet->setCellValue('A3', 'Position');
            	$sheet->setCellValue('B3', $header->title);
            	$sheet->setCellValue('A4', 'Location');
            	$sheet->setCellValue('B4', $header->location);

                $sheet->fromArray($dataArray, null, 'A7', false, false);

                $sheet->row(1, function ($row) {

                    $row->setFont(array(
                        'bold' => true
                    ));

                });

            });
		})->download('xlsx');

Tapi selalu error: Object of class stdClass could not be converted to string

Adakah yg keliru dari kodingan tersebut?