Do you see those RED lines I surrounded with WHITE? Those show that your signature is way too high, more exactly 310x160 pixels, the limits being 500x150. To fix this, you need to re-size the picture. Luckily for you, I already re-sized the image and made it 291x150 pixels, enough to fit in the rules. All you have to do is to copy paste the code in your signature control panel.