Error when using XRANDR to add new resolution

Question

I've been having some difficulty adding a new resolution using XRANDR and outputting it to my second monitor, which is a Panasonic Viera TX-P42G10E. This is what I run on my Ubuntu 12.04 LTS:

kapacs@LINUX:~$ cvt 1920 1200 60
# 1920x1200 59.88 Hz (CVT 2.30MA) hsync: 74.56 kHz; pclk: 193.25 MHz
Modeline "1920x1200_60.00"  193.25  1920 2056 2256 2592  1200 1203 1209 1245 -hsync +vsync

I add it using --newmode and it successfully appears:

kapacs@LINUX:~$ xrandr
Screen 0: minimum 8 x 8, current 1024 x 768, maximum 8192 x 8192
VGA-0 connected 1024x768+0+0 (normal left inverted right x axis y axis) 0mm x 0mm
   1024x768       60.0*+
   1360x768       60.0     59.8  
   1152x864       60.0  
   800x600        72.2     60.3     56.2  
   680x384       119.9    119.6  
   640x480        59.9  
   512x384       120.0  
   400x300       144.4  
   320x240       120.1  
LVDS-0 connected (normal left inverted right x axis y axis)
   1920x1200      60.0 +
DVI-D-0 disconnected (normal left inverted right x axis y axis)
  1920x1200_60.00 (0x2b5)  193.2MHz
        h: width  1920 start 2048 end 2256 total 2592 skew    0 clock   74.5KHz
        v: height 1200 start 1201 end 1204 total 1242           clock   60.0Hz

Then, when I try to assign it to the VGA-0 output terminal, it hits me with this.

kapacs@LINUX:~$ xrandr --addmode VGA-0 1920x1200_60.00 
 X Error of failed request:  BadMatch (invalid parameter attributes)
   Major opcode of failed request:  153 (RANDR)
   Minor opcode of failed request:  18 (RRAddOutputMode)
   Serial number of failed request:  27
   Current serial number in output stream:  28

Any advice is greatly welcome, I've tried the xorg.conf version as well and it did not work. Tutorial I tried. Thank you!