NX problems

Hello:

I've recently installed knoppix 3.8.1 in my computer. I've been using knoppix 3.6 and the nx server worked great, but I've installed the new version and nx doesn't work. It says (in the client):

server is not installed or NX remote access disabled

But it is installed and the server is running. I've tried reinstalling but the problem is the same. Users are created with
nxserver --adduser username and
nxserver --passwd username

Anyone has any idea? Is very important for me, I have to use it everyday. I've changed nothing since installation, so where doesn't work?

Thanks in advance.