Debian 8 Apache 2.4.10 ErrorDocument overload not working

Question

I've spent many hours with testing different solutions and googling but not succeeeded yet. I'm using VirtualHost with one site for my web site (/var/site1/www/html/) and another for managing maintenance pages or ErrorDocument (/var/msite2/www/html).
My final goal is to allow some IPs to access the site1 during maintenance phase. For denied IPs, I want them to be redirected to a maintenance page responding to the Error 503.
IPs filtering is working. My problem is about redirection.
In the site1 configuratipon file, in the VirtualHost, if I set ErrorDocument 503 "Bad luck !!!", the text is dispalyed on thedenied IP browser.
When I try to set ErrorDocument 503 /var/msite1/www/html/Error503.html, I've got the default 503 text message plus one telling that the system is unable to find the Error503.html.
Does anyone has a real procedure for that ?

Answer 1

Finally, I reset my mind and found a solution to my problem using environmnet variable, rewriterule ...

# Define Environment Variables
SetEnvif Request_URI ".*" ENVIRONMENT=MAINTENANCE
# Directory for site content
<Directory "/var/site1/www/html">
 AllowOverride All
 Require all granted
 ...
</Directory>
<Directory "/var/msite2/www/html">
 AllowOverride All
 Require all granted
</Directory>
# Maintenance redirection
UseCanonicalName On
RewriteEngine On
RewriteMap exceptions /var/msite2/exceptions.map
RewriteCond %{ENV:ENVIRONMENT} =MAINTENANCE
RewriteCond ${exceptions:%{REMOTE_ADDR}} !=OK
RewriteRule ^/(.*)$ /var/msite2/www/html/$1

It works fine now.