Illustrator :: Eraser On Traced Image?

I imported the scanned image to illustrator and then used object->image tracer and converted it to a vector graphic with area fill and no stroke. So far so good.
 
I now want to erase little mistakes in the drawing, that look like this

if I use the eraser, this happens:
  
so the path is weirdly bend around the stroke of the eraser, which obviously isn't what I wanted to achieve. In all the videos I watched about the eraser, it worked fine and if I just create an area with the blob brush and erase a part of that, that works fine as well. What's so different with the traced image?