When following your link, we didn't get a blank page but a "404" error page.
A blank page is generally the symptom of a PHP fatal error.
In this case, you should have an error log file in your server that should provide you more information on the reason of the error.
You can also check the permission of the files and folders to verify that you can have access to the slave site directory.
You can for example install the "hello.php" into the slave site "deploy folder" to verify that you have access to the subdirectory.
If you want that we have a look on your server and help you configure your environment, this is also possible with our billable support that you can order at
www.jms2win.com/en/joomla-multisite?page...35&category_id=1