use two or more tables from database in editor

I use codeigniter to create editor datatables, it was normal for one table, but when i use two tables, there problem in ajax, here is model.

public function getNdsar2020($post)
{
// Build our Editor instance and process the data coming from _POST
Editor::inst( $this->editorDb, 'ndsar2020' )
    ->fields(
        Field::inst( 'no_ndsar' ),
        Field::inst( 'tgl_ndsar' ),
            // ->validator( Validate::dateFormat( 'd/m/y' ) )
            // ->getFormatter( Format::dateSqlToFormat( 'd/m/y' ) )
            // ->setFormatter( Format::dateFormatToSql( 'd/m/y' ) ),
        Field::inst( 'surat' ),
        Field::inst( 'tgl_surat' ),
        Field::inst( 'keterangan' ),
        Field::inst( 'hal' )
    )
    ->process( $_POST )
    ->json();
}

public function getPelanggan2020($post)
{
// Build our Editor instance and process the data coming from _POST
Editor::inst( $this->editorDb, 'pelanggan_2020' )
    ->fields(
        Field::inst( 'nama_pelanggan' ),
        Field::inst( 'idpel' ),
        Field::inst( 'tarif_lama' ),
        Field::inst( 'daya_lama' ),
        Field::inst( 'tarif_baru' ),
        Field::inst( 'daya_baru' ),
        Field::inst( 'jumlah' ),
        Field::inst( 'alamat' ),
        Field::inst( 'daerah_kerja' ),
        Field::inst( 'kontak' )
    )
    ->process( $_POST )
    ->json();
}

}

****and then here my editorlib.****

public function process($post)
{   
    // DataTables PHP library
    require dirname(__FILE__).'/Editor-PHP-1.9.2/lib/DataTables.php';

    //Load the model which will give us our data
    $this->CI->load->model('Sar_model');

    //Pass the database object to the model
    $this->CI->Sar_model->init($db);

    //Let the model produce the data
    $this->CI->Sar_model->getNdsar2020($post);

    //Let the model produce the data
    $this->CI->Sar_model->getPelanggan2020($post);

}

i check the ajax load result with jsonlint, and here is the problem .

Would you give me solution ??