X11 forwarding problems in FreeBSD 6.2

[Pollywog]

I am having some problems with X11 forwarding. I can do X11 forwarding via ssh 
between two machines running Linux, but if I try to do this from FreeBSD 
(KDE) to either of the Linux machines, it only works if I use startx to start 
KDE on the fbsd machine (a laptop). If I start KDE from kdm, I get errors 
that go like this when I start the KDE app on the remote host running Linux:
 pollywog at slider:~$ kate
 Xlib: connection to "localhost:11.0" refused by server
 Xlib: Invalid MIT-MAGIC-COOKIE-1 key
 kate: cannot connect to X server localhost:11.0
 
 My configurations for ssh are similar on all hosts:
 
 sshd_conf has
 AllowTcpForwarding yes
 X11DisplayOffset 10
 X11UseLocalHost yes
 XAuthLocation /usr/local/bin/xauth
 
 ssh_conf has
 Host slider
 HostName 192.168.0.1
 ForwardAgent yes
 ForwardX11 yes
 ForwardX11Trusted yes
 PubkeyAuthentication yes
 Protocol 2