if downloaded from here (or a similar source):
http://sourceforge.net/projects/fourever/files/
although described in the manual
http://sourceforge.net/p/fourever/code/HEAD/tree/projektassistent/trunk/docs/help/de/help.html#l24
we get an error:
startup-en.*
saysThe chosen directory does not contain the V-Modell XT (missing file V-Modell-XT.xml). Please correct your choice.
startup-de.*
saysDas angegebene Verzeichnis enthält nicht das V-Modell XT (zumindest nicht die benötigte Datei V-Modell-XT.xml. Bitte passen Sie Ihre Auswahl entsprechend an.
It took me quite some research and contacting support to find this out ... This is due to the fact that the sourceforge repo only contains the tools, not the model itself (which is not very obvious).
That's why one should first install it via the official installer: http://www.cio.bund.de/DE/Architekturen-und-Standards/V-Modell-XT/vmodell_xt_node.html and then maybe update the tools via sourceforge binaries.