12.04 - Ubuntu splash won't change?

How do i change the boot splash background color to be black, not purple?
I have edited /lib/plymouth/themes/default.grub to

if background_color 0,0,0 ; then
clear
fi

then I also changed these rows in /lib/plymouth/themes/ubuntu-logo/ubuntu-logo.script as follows:

Window.SetBackgroundTopColor (0.0, 0.00, 0.0); # Nice colour on top of the screen fading to
Window.SetBackgroundBottomColor (0.0, 0.00, 0.0); # an equally nice colour on the bottom

Then in configuration editor on apps/gnome-session/options/ i have set splash_image to /lib/plymouth/themes/ubuntu-logo/ubuntu_logo.png

The result is a bit weird... When I start the machine, a blank purple screen appears white it boots then the white ubuntu logo and the progress dots appear on a black screen for just a second or two before the login screen. Aren't they supposed to replace this purple screen in the whole boot process? When I shut down or reboot the machine, it is only as it is supposed to according to my settings, i.e. with black background, white ubuntu logo and progress dots. How to fix this? Any ideas? I don't like this purple background on every boot at all... :(
This is on ubuntu 12.04.