PSE is cropping the sides of my prints

Hello everyone,

After years of only using Corel products I'm trialing Photoshop Elements, so would be very grateful for some help with a few questions. The first of those is a cropping problem, I'm attempting to print a landscape orientated photo on the to top half of an A4 sheet; the selected print size is 12.7 x 17.8, and in the preview window it looks absolutely fine, but when I print the image it comes out the correct height but cropped on both sides, so basically square. What am I missing?

Thanks for any help