Probably a permission issue then. I just installed IDManager V20 using the installer exe on a Windows 2012 server. It came up in Italian initially with this error message:

- 2015-12-21_11-58-02.jpg (47.01 KiB) Viewed 10959 times
I then gave the IIS_IUSERS group full access to that folder. Then the error went away.
And I confirmed that the LANGUAGE=ENG or LANGUAGE=ITA in the DBXML\root.xml file is what determines the language setting for IDManager. So it isn't being read properly by IIS.
...jack