change xorg video resolution

[freenity]

Hello. I have a strange problem with my xorg configuration. It only runs at
1024x768, but I want to change it to 1280x1024. This is the screen section
from my /etc/X11/xorg.conf

Section "Screen"
        Identifier "Screen0"
        Device     "Card0"
        Monitor    "Monitor0"
        SubSection "Display"
                Viewport   0 0
                Depth     16
                Modes    "1280x1024"
        EndSubSection
        SubSection "Display"
                Viewport   0 0
                Depth     16
                Modes   "1280x1024"
        EndSubSection

EndSection

But it steal running at 1024x768.
Thanks fro any ideas.