Nginx rtmp secure link?

Question

linux

Hello everyone, there was one problem, I could not solve it myself, help me solve the problem!
Task:
Implement rtmp address security using the nginx rtmp + secure link module
Here is the actual nginx.conf config

http {
server {
location /on_play {

   # set connection secure link
   secure_link $arg_st,$arg_e;
   secure_link_md5 mysecretkey$arg_app/$arg_name$arg_e;

   # bad hash
   if ($secure_link = "") {
      return 501;
   }
   # link expired
   if ($secure_link = "0") {
      return 502;
   }
      return 200;
  }
}
}

rtmp {
    server {
        listen 1935;
        notify_method get;

        application movies {
           live on;
           on_play http://mp4.sitename.com/on_play;
        }
    }
}

I removed extra lines from the config file, such as:

user www-data;
#выставите worker_processes  равное:  cat /proc/cpuinfo | grep "processor" | sort -u | wc -l
worker_processes  24;
error_log  /var/log/nginx/error.log;
pid     /var/run/nginx.pid;

Here is PHP code

$mysecretkey = "mysecretkey";
$path = "movies";
$filename = "sample.mp4";
$expiry = strtotime("+1 hour");
$b64 = base64_encode(md5($mysecretkey.$path.$expiry,true));
$b64u = rtrim(str_replace(array('+','/'),array('-','_'),$b64),'=');
$url = "rtmp://mp4.sitename.com/$path/".$filename."?e=$expiry&st=$b64u";

Результат скрипта:
rtmp://mp4.sitename.com/movies/sample.mp4?e=1455018026&st=3_JifIdDmk8Z4CYu_S3vmQ

и ошибка:
rtmp://mp4.sitename.com/movies/sample.mp4?e=1455018026: Unknown error occurred

Maybe I'm doing something wrong? maybe I made a mistake somewhere? I will be very grateful for your help. thanks in advance!