[Freesurfer] tksurfer doesn't work

Dear Freesurfer Experts

I have a Macbook 2GHz Intel Core 2 Duo (MAC OSX Version 10.4.11) and just installed Freesurfer v4.1.0. I followed the installation and setup steps of the freesurfer homepage and everything seemed to work well. When I finally tried the "tksurfer bert rh pial" command I got an error message called: "GLUT: Fatal Error in tksurfer.bin: could not open display: ". Later on I saw, that tksurfer actually works, but only when I type the command into the X11 terminal. Is this correct? Do I always have to work with the X11 terminal, or did I do something wrong? Thanks for your help in advance!

Cheers,

Rafael Huber