i have a problem with xrandr i successfully executed the following :

#cvt 1900 1080
#xrandr 1900x1080 170.75  1904 2024 2224 2544  1080 1083 1093 1120 -hsync +vsync

but unfortunately the following command :

#xrandr --addmode VGA-0 1900x1080

returned the following error :

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:  29
Current serial number in output stream:  30

the following command output might help in identifying problem :

#glxinfo |grep -i opengl
OpenGL vendor string: NVIDIA Corporation
OpenGL renderer string: GeForce 310M/PCIe/SSE2
OpenGL version string: 3.3.0 NVIDIA 310.14
OpenGL shading language version string: 3.30 NVIDIA via Cg compiler
OpenGL extensions:

#lspci |grep -i vga
01:00.0 VGA compatible controller: NVIDIA Corporation GT218 [GeForce 310M] (rev a2)

any ideas what's gonna be wrong ?