Missed feedback proves nothing. I have missed hundreds of feedbacks on ebay and at least a few dozen on GB simply because people just will not leave feedback, sellers and buyers. This has nothing to do with the actual auction - its just people. I've had many auctions where they wouldn't even answer an email to see how they liked the item. You send it, they get it, that's it. No more contact, no feedback, nothing. I quit thinking about it. Now if I sell an item I always give the buyer a positive after they pay for it but they still won't do mine. I guess its just a step they don't want to be bothered with.