I want to do some customization on seven administation theme, I won't to copy it in my themes folder, I want to create a subtheme of it, it doesn't work for me. this is my info file
name = SEVEN SUB description = a Seven subtheme base theme = seven core = 7.x stylesheets[all] = style.css
when I replace Seven by a theme already exists in my sites/all/themes, my theme inherits it, but for core themes it doesn't. I tried to specify the path of seven, themes/seven and /themes/seven doesn't fix the problem.