My eraser is not working on Microsoft paint

My eraser by it self is fine when you use left click. But when i right click to erase only one color it wont do anything!

EXAMPLE:

So I am doing a drawing of a cat and I did an outline with red pencil. Then I use a black paintbrush over it. When I try to erase the red pencil by holding the right button. It didn't erase anything.

Any advice is helpful for me but the answer would be amazing.

Also I restarted my computer twice.

Thanks!