feedback Woes, again

I cant leave feedback for a member who bought an item...I click on add feedback for the buyer and proceed to fill out the info and when I try to submit it, I keep getting an error stating I have to be the buyer or the person who created the ad to leave feedback.....Well , I was the creator of the deal thread and that was the deal thread I put in there.....The buyer did not post in the add at all, he just PM'ed me and we did it through conversations, maybe that is why?????