[Solved] Black bar added on the right of the monitor after changing resolution using xrandr

I’m running UBUNTU 17.10 on a Samsung SyncMaster 713n monitor via VGA-0. It wouldn’t display the monitor’s native resolution, so I created a custom resolution using cvt and xrandr as follows:

xrandr --newmode “1280x1024_59.90” 108.70 1280 1360 1496 1712 1024 1025 1028 1060 -HSync +Vsync

xrandr --addmode VGA-0 1280x1024_59.90

xrandr --output VGA-0 --mode 1280x1024_59.90

It provides me with the proper resolution, however it appears to have added a black bar of a few cm’s to the right of the screen .If I screenshot it, it comes up fine, but I see a 3 mm black bar on the right side of my screen.it appears just fine on windows and the auto-adjust button on my monitor does’nt seem to be doing anything . can anyone provide me a method to get rid of the black bar.any help would be appreciated,thank you.

fixed it,had to adjust the image manually from the monitor settings.