Custom Error Page Is not Working

hello there
I have an error page which is working locally with a sentence like this in my .htaccess file:
ErrorDocument 404 http://www.correspondingdomain.com/notfound.php

For example if I browse a page of the site that does not exist and I do it on local my server installation then I get the remote page: http://www.correspondingdomain.com/notfound.php
Nonetheless, it turns out that when I try the same thing but browsing the page in the remote server which is not mine, then the default error page is loaded instead of mine when the user browser a page that does not exist.

Do you know why this might happen?
I just thought that it might be because the hosting company did not enable the allowoverride. Do you know if there would be any work around in case they did not enable it and do not want to enable it?
Thanks in advance

It is solved now. The problem was that the error page had to be set through a form of the control panel from my hosting company because it seems that they do not pay attention to this ErrorDocument clause in the .htaccess file.
Thanks though.