I changed the file with a big black square: pick up the color from it.
First I will thank you for your big effort to help me. I had found that it's my pc which is fooling around with me, when I save. I have no problems to choose RGB 000 (or 160/0/0) but when I reopen my drawing there seems to be changes in the pixels. Not only in black
Now I have moved my drawing to my sons computer. I'll reckon she is ok now
[Edit] She is moved down at this page