Are yo trying to use SSH for forwarding, or not. It seems like you are trying to mix + match two methods here. One for forwarding with SSH, and that isn't used for ssh.
If you want to forward via SSH all you should have to do on your client is ssh -X remotehost. You shouldn't need to do anything in your session on the server once you have connected. No xhost, or exporting is required.
One thing I do wonder though is if your SSH server is properly setup for X11 forwarding. This is an option that isn't always on by default. See your sshd_config X11Forwarding setting.