Cannot launch remote apps on X

[diego <ddc_prueba@yahoo.es>]

Hello, I have a knoppix just installed and network configured with a
fixed IP (lets say 172.16.10.1) and working right. The problem is that
if I do:

1) export DISPLAY=:0; xclock   ==> It works

2) export DISPLAY=172.16.10.1; xclock  ==> It cannot connect to X


I have done the "xhost +" part, also check that xfont is on :7100 port
and not in :-1

What am I missing? Thanks a lot for your help.