Trying to get property of non-object

Permisi Master, ini salahnya dimana yah? mohon bantuannya

Controller

function detail($table, $id)
	{
		if ($table == 'sekolah') {
			$data['menu_sekolah'] = $data['menu_verifikasi'] = 'active';
			$r = $data['sekolah'] = $this->GeneralModel->get_data_sekolah_by_id($id);

			$data['page_header'] = $r->nama_sekolah;
			$data['b_crumb'] = array (
				'#' => 'Verifikasi',
				base_url('admin/sekolah') => 'Sekolah',
				'' => $r->nama_sekolah
			);

			$this->template->admin('admin/detail_sekolah', $data);
		}else if ($table == 'siswa') {
			$data = $this->AdminModel->get_data_siswa_lengkap_by_id($id);

			$data['page_header'] = $data['siswa']->nama_lengkap; //NOTICE disini
			$data['b_crumb'] = array (
				'#' => 'Verifikasi',
				base_url('admin/siswa') => 'Siswa',
				'' => $data['siswa']->nama_lengkap //NOTICE disini
			);

			$this->template->admin('admin/detail_siswa', $data);
		}
	}

Model

function get_data_siswa_lengkap_by_id($id)
	{
		$where['ID_siswa'] = $id;

		// get from data siswa
		$q = "SELECT * FROM siswa a, sekolah b, status c WHERE a.ID_sekolah = b.ID_sekolah and a.status_pendaftaran = c.ID_status and a.ID_siswa = $id";
		$siswa = $this->db->query($q);
		$siswa = $siswa->row();

		// get from data alamat
		$q = "SELECT * FROM alamat a, provinsi b, kota c, kecamatan d WHERE a.kecamatan=d.ID_kecamatan and d.ID_kota=c.ID_kota and c.ID_provinsi=b.ID_provinsi and a.ID_siswa = $id";
		$alamat = $this->db->query($q);
		$alamat = $alamat->row();

		// get from data orangtua
		$orangtua = $this->db->get_where('orangtua', $where);
		$orangtua = $orangtua->row();

		// get from persyaratan
		$persyaratan = $this->db->get_where('persyaratan', $where);
		$persyaratan = $persyaratan->row();

		// get data from un
		$un = $this->db->get_where('un', $where);
		$un = $un->row();

		// get data jurusan
		$jurusan = $this->db->get_where('pilihan', $where);
		$jurusan = $jurusan->row();
		if ($jurusan != NULL) {
			$w['ID_jurusan'] = $jurusan->pilihan1;
			$j1 = $this->db->get_where('jurusan', $w);
			$j1 = $j1->row();
			$w['ID_jurusan'] = $jurusan->pilihan2;
			$j2 = $this->db->get_where('jurusan', $w);
			$j2 = $j2->row();
			$data['jurusan'][0] = $j1;
			$data['jurusan'][1] = $j2;
		}else {
			$data['jurusan'] = $jurusan;
		}

		$data['siswa'] = $siswa;
		$data['alamat'] = $alamat;
		$data['orangtua'] = $orangtua;
		$data['persyaratan'] = $persyaratan;
		$data['un'] = $un;

		return $data;
	}

dan muncul notice seperti ini

A PHP Error was encountered

Severity: Notice

Message: Trying to get property of non-object

Filename: controllers/Admin.php

Line Number: 508

Backtrace:

File: C:\xampp\htdocs\myproject\application\controllers\Admin.php Line: 508 Function: _error_handler

File: C:\xampp\htdocs\myproject\index.php Line: 315 Function: require_once