Configuring xdm

[Fractal]

I have FreeBSD 5.3-RELEASE with Xorg X server installed on
my machine and I have problems with configuring xdm.
Namely, the problem is: if I run xdm on X display :0, and
set session program, /usr/X11R6/bin/wmaker for example, in
~/.xsession, when I try to login using xdm, after few seconds of
blank screen I see again xdm login prompt, but no wmaker.
After this, my ~/xsession-errors contain message like this:
"Connection to display :0 refused by server". I tried following
command in .xsession:
xinit /usr/X11R6/bin/wmaker -- /usr/X11R6/bin/Xorg :1
This worked, but in this case after login I have two X displays
on different terminals: one with only X server screen with cross
cursor, and another with wmaker. Does it mean that if I run xdm
on display :0 then I cannot run session program on the same display?

Thanks.