You are welcome. To all interested people, the problem was the chart background color. It was on None, so the rectangle fill was not visible (see why in this article).
So I changed back to black and all was resolved.
posted 16 hours ago.
I changed the chart background color to black, not the object. I used Teamviewer and changed MT4 chart properties(F8).
You were answering with code on a topic which has nothing to do with code.