Почему не работает авторизация через Htaccess?

Вот htaccess

Options -Indexes
ErrorDocument 404 /404.php

AuthType Basic
AuthName "Password Protected Area"
AuthUserFile /web/site.ru/public_html/.htpasswd
Require valid-user

php_flag allow_call_time_pass_reference 1
php_flag session.use_trans_sid off

#php_value display_errors 1

#php_value mbstring.func_overload 2
#php_value mbstring.internal_encoding UTF-8

Options +FollowSymLinks
RewriteEngine On
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-l
RewriteCond %{REQUEST_FILENAME} !-d
RewriteCond %{REQUEST_FILENAME} !/bitrix/urlrewrite.php$
RewriteRule ^(.*)$ /bitrix/urlrewrite.php [L]
RewriteRule .* - [E=REMOTE_USER:%{HTTP:Authorization}]

DirectoryIndex index.php index.html

ExpiresActive on
ExpiresByType image/jpeg "access plus 3 day"
ExpiresByType image/gif "access plus 3 day"

Вот .htpasswd
admin:$apr1$z4LVTkyo$Vn6IXzajiNAVa7iilSZ18.

После ввода логина и пароля - 500 ошибка.