I'm not sure you know what OLWS is--do you?
Like NdAppy, I'm not buying that she's negative. There was recently another poster on here who had a mare that the previous owners had told her tested negative, though she looked like a positive. She bred her to her positive stallion, and had a lethal white foal which, of course, had to be euthanized. You cannot trust what people say, and you cannot trust lab results unless they are from a reliable, reputable institution.