Problem when opening the Web Client for NAV 2013

Hi everyone,
I have three versions of NAV installed on my machine: 2009 R2, 2013 and 2013 R2.
I have the Web Client installed (default installation) for both versions(2013 and 2013 R2). 2013 was installed first.
When I try to open the Web Client for NAV 2013, via the following URL:


I get the followin error displayed in the browser:

Server Error in '/' Application.

The resource cannot be found.

Description: HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable. Please review the following URL and make sure that it is spelled correctly.

Requested URL: /DynamicsNAV/70/WebClient/default.aspx

What am I missing?
If it is a problem of ports, what port number can I use, rather than 7046?
Thanks in advance :)