Digital photo frame. Hi, I have bought a Matsui Digital photo frame model PF-A701W as a Christmas

Question

Hi, I have bought a Matsui Digital photo frame model PF-A701W as a Christmas gift and am trying to preload some photos onto a USB flash RAM stick so it's ready to go. I know that only JPEG formats are supported and I've reduced the size of the photos down via Adobe PhotoShop, again making sure they are resaved in JPEG format. Thing is , the photo frame just stays "Loading" forever and displays nothing! Any ideas?