503 Service Temporarily Unavailable

hi,
I want to convert my video using ffmpeg when node saved.

I created ffmpegRule, triggered when "After saving new content".

I choose PHP->Execute custom PHP code

I entered the code

if(    isset($node->field_video)&&     isset($node->field_video[0])&&     ($node->field_video[0]['fid']>0)   ) {
  $out=array();
  exec("ffmpeg   -an -ss 00:00:10 -an -r 1 -s cif -vcodec mjpeg -vframes 1 -y /home/nerkn/sarkisozu.web.tr/ffmpeg%d.jpg -i \"/home/nerkn/sarkisozu.web.tr/{$node->$node->field_video[0]['filename]}\"", $out);
  exec("mv /home/nerkn/sarkisozu.web.tr/ffmpeg1.jpg /home/nerkn/sarkisozu.web.tr/{$node->nid}.jpg", $out);
  $out=implode("<br />", $out);
  watchdog('content', '@type: ffmpeg %title, %out', array('@type' => $node->type, '%title' => $node->title, '%out'->$out));
  }

But I cant save this code!

I get 503 Service Temporarily Unavailable

The server is temporarily unable to service your request due to maintenance downtime or capacity problems. Please try again later.

Can any one guess what going on?