Reverse proxy with lotus webmail

I’am a newbie and I’m trying to configure nginx as a reverse proxy on
443 to 443 port of an internal domino server but It doesn’t work. I can
reach the login page and if I use wrong credentials I have an error from
domino internal server instead when I use correct credentials the login
page is proposed again with no error. My config is

server {
    listen  443;
    ssl     on;
    ssl_certificate         myserver.pem;
    ssl_certificate_key     myserver.key;
    ssl_session_timeout     5m;

    server_name  name.of.external.srv;

    error_log /tmp/error.log debug;

    location / {
        proxy_pass         https://name.of.internal.srv;
        proxy_redirect     off;
        proxy_set_header   Host             $host;
        proxy_set_header   X-Real-IP        $remote_addr;
        proxy_set_header   X-Forwarded-For 


        client_max_body_size       10m;
        client_body_buffer_size    128k;

        proxy_connect_timeout      90;
        proxy_send_timeout         90;
        proxy_read_timeout         90;

        proxy_buffer_size          4k;
        proxy_buffers              4 32k;
        proxy_busy_buffers_size    64k;
        proxy_temp_file_write_size 64k;

Someone can help?