Oreck Steam Mop Left White Mark on Wood Floor?

I've been using my Oreck mop for quite sometime now and yesterday I found gum on my wooden floor. I used my Oreck to get it up and it just wouldn't come up. So I placed the Oreck on the gum so that maybe the steam would break it up and all it did was leave a white mark on the floor. Any ideas?

By Ron F.