How well do they erase? I just bought one for home use and I don't know if it is defective or I am asking too much from my new whiteboard. It is very hard to erase. I've two packs of markers, both different makes, and get the same results. With this new pack and the black marker, the actual text erases but leaves a ghost image with a black smear. So now I have a gray cloud with white text inside...if that makes sense. If I look at the board at a certain angle you can still a lot of the text I've written and erased. Am I doing something wrong or is this really how they are supposed to be? Maybe different brands are better than others? Maybe I need to return it and get a chalk board. I know how those are supposed to work.