the 3D cube

  I don't if here is the write place to ask about this: the cube doesn't rotate to the top and bottom faces and when I type compiz in the terminal, it gives this output:

compiz
Checking for Xgl: not present.
xset q doesn't reveal the location of the log file. Using fallback /var/log/Xorg.0.log
Detected PCI ID for VGA:
Checking for texture_from_pixmap: present.
Checking for non power of two support: present.
Checking for Composite extension: present.
Checking screen 1NVIDIA: could not open the device file /dev/nvidiactl (Permission denied).
Comparing resolution (1440x900) to maximum 3D texture size (8192): Passed.
Checking for Software Rasterizer: Not present.
Checking for nVidia: present.
Checking for FBConfig: NVIDIA: could not open the device file /dev/nvidiactl (Permission denied).
present.
running under gnome seesion, checking for gnomecompat
Checking for Xgl: not present.
NVIDIA: could not open the device file /dev/nvidiactl (Permission denied).
/usr/bin/compiz.real (video) - Warn: No 8 bit GLX pixmap format, disabling YV12 image format
/usr/bin/compiz.real (cube) - Warn: Failed to load slide: /usr/share/gdm/themes/Human/ubuntu.png
/usr/bin/compiz.real (trailfocus) - Warn: Attempting to define start higher than max windows.

any help on how to enable them?