I have a new install of osTicket. In Admin > Settings, my helpdesk URL is http://10.115.0.56(http://10.115.0.56)
When I go to this url, all I get is the default apache page instead of the osTicket page where users can submit tickets...
index.php
I found out what my problem was. I had an index.html in the root directory which apache served before index.php. I removed index.html and i'm good now.
I was going to ask you what dir you installed the ticketing system to, but you found your own solution before I could ask. :)
Alternatively you could have changed the order in which Apache looks for files to load. Which is done via the DirectoryIndex directive. But you are better off just removing the index.html file.