Laravel ffmpeg Encoding failed in watermark filter

ffmpeg show error while encoding when add watermark filter:

FFMpeg::fromDisk('public')
            ->open($path)
            ->addFilter(function ($filters) {
                $filters->resize(new Dimension(640, 480));
                $filters->watermark(public_path().'/storage/images/mark.png', [
                     'position' => 'relative',
                     'bottom' => 240,
                     'right' => 320
                ]);
            })
            ->export()
            ->toDisk('public')
            ->inFormat((new \FFMpeg\Format\Video\X264('libmp3lame', 'libx264'))->setKiloBitrate(40))
            ->save('thumbnail/'.$filename);

when i remove filter->watermark it is working, so what is the problem ?

via Chebli Mohamed