Bought Yonex Duro Z-Strick racket, but the serial No. on the shaft is not "JP" instead there's very weak mark that looks like "XP", which country is it? Does it mean it's an experimental racket, not final production version? Note that the price I paid is a fair market value. The I email the store, but get no response at all. So I am still keeping the racket. I am very disappointed about Rakuten because of this.