I am using xubuntu 9.10 on a aao
the default settings did not support any other screen than 1024:900 and I have used xrandr to create new configurations, but when it comes to adding them it says I cannot...I have tried with VGS, DVI and others and it says it's wrong

abelito@Ernestino:~$ xrandr
Screen 0: minimum 1024 x 768, current 1024 x 768, maximum 1024 x 768
default connected 1024x768+0+0 0mm x 0mm
1024x768 61.0*
800x600_50.00 (0x10c) 30.8MHz
h: width 800 start 824 end 896 total 992 skew 0 clock 31.0KHz
v: height 600 start 603 end 607 total 621 clock 49.9Hz
656x340_50.00 (0x10d) 14.2MHz
h: width 656 start 672 end 736 total 816 skew 0 clock 17.5KHz
v: height 340 start 343 end 353 total 356 clock 49.1Hz
abelito@Ernestino:~$ xrandr --addmode VGA-O 800x600
xrandr: cannot find output "VGA-O"

any help please?