i recently ended a sale for this ad http://www.sevenstring.org/forum/gear-sale-trade-wanted/271319-seymour-duncan-nazgul-7-string.html and i am trying to leave positive feedback for the buyer. it just says: Please make sure you are not leaving duplicate feedback! Check the comments before submitting feedback to make sure you do not rate the person for a the same item(s) twice. which it is not a duplicate. help!