xhost does not work as expected

[Frank Bonnet]

Hello

I am at 6.0 with xorg and I cannot remotely use a GUI backup software ( netvault)
because I am not able to use properly the xhost command.

On the server I set ( csh ):

setenv DISPLAY hostname:0.0

On the client I set

xhost + hostname

but I am not authorized to use the client display from the server
is there some special X11R6 configuration to use this feature ?

thank you
-- 
Frank Bonnet