Update:
I kept researching for a possible solution, and I found that the use of "index2.php" in Joomla 1.5 is deprecated. The AJAX function calls for a URL like this one:
www.slave-domain.com/index2.php?option=com_webeecomment
I read that it should be like this one instead:
www.slave-domain.com/index.php?option=co...t&tmpl=component
I tried to replace the deprecated link with the correct one, but the result is still the same: the page loads the CSS stylesheet from the Master domain, and not for the slave domain. The HTML of the loaded page contains this:
link rel="stylesheet" href="/templates/master_template/css/template.css" type="text/css"
instead of
link rel="stylesheet" href="/templates/slave_template/css/template.css" type="text/css"
thank you.