I select "product name" field under the "add filter".
Then if I add "-balls", that works fine it blocks out "golf balls" which I dont want in my listing as im wanting irons only.
But then if I do exactly the same and add "-balls" "-shoes" ( as I dont want balls or shoes in this listing, it comes up with that error.
Its like I cant have 2 negative keywords for the "product name", im only allowed 1.
Hope that makes sense