start fgfs = Assertion failed: (window->Window.VisualInfo != NULL)

Hello folksI installed the flightgear port on my freebsd 5.3 system. The fgfs version is0.9.6.The installation went well, but now I cannot start the simulator with "fgfs".I get this error message:bash-2.05b$ fgfsAssertion failed: (window->Window.VisualInfo != NULL), functionfgOpenWindow, file freeglut_window.c, line 300.Abort trap (core dumped)I reinstalled the freeglut toolkit, but I get still this message.Any suggestion what could be wrong ?Greetings Karim