That symbol shows up on photos that are too low-res for printing. If your heart is set on that photo, we recommend resizing the image.
For print sets, we recommend images that are 2-5 MB in size and have a resolution of at least 150 PPI. These are perfect for printing your Instagram and camera roll images!
For wall art, the best images will be 5-10 MB and 300 PPI. If you want a nice crisp photo use the original photo, not an Instagram or screenshot, and be sure not to zoom in too much if you're cropping the photo.