Export PDF blade view using laravel-dompdf

i try to export a blade view using the package from : https://github.com/barryvdh/laravel-dompdf

but i get an error array_merge(): Argument #2 is not an array

here my controller :

public function ExportPDF($licencie)
    {

        $pdf = PDF::loadView('licencie_structure.show', $licencie);
        return $pdf->download('invoice.pdf');

    }

here my route :

Route::get('/export/pdf/{licencie}',
    [
        'as' => 'export.pdf',
        'uses' => 'LicencieStructureController@ExportPDF'
    ]);

here my button from my blade view :

 {!! link_to_route('export.pdf', 'Export to PDF', [$licencie] , ['class' => 'btn btn-info'])!!}

someone knows why i get this error ? thanks a lot in advance .

via Mathieu Mourareau