add_editor_style problem

Hi

I urgently would like to change the looks of my backend post editor. Found how to do it in this : article and this article .

I did what it says. Like adding the described
add_editor_style(‘editor-style.css’)
in the functions.php (of the theme I presume) file.
But also
add_editor_style(get_stylesheet_uri() . ‘editor-style.css’)
and
add_editor_style(get_stylesheet_uri() . ‘style.css’);
or
add_editor_style(get_stylesheet_uri() . ‘/style.css’);
or
add_editor_style(get_stylesheet_uri());

But nothing changes. I checked each time in firebug whether the file is loaded and it’s not.
I changed editor-style.css content with the style.css content and again no changes.

I use simple tineMCE no plugins.
Why my tinyMCE doesn’t use the editor-style.css?!!
And why the editor file is not loaded?

BTW all kinds of php & css files do get loaded: post.new.php thickbox.css?ver windows.css?ver and many more.

thx in advance