My dry transfer sheets are a few years old. What am I doing wrong?
Dry transfers eventually go bad. They are sticky ink printed on wax paper; pressing them against another surface causes the ink to stick to the surface better than it sticks to the wax, and it transfers. With age the ink drys out and becomes hard and less sticky and it will no longer transfer. I haven't tried this, but for small transfers like chalk marks, you might try gently warming the spot on the sheet over an incandescent light bulb and see if it transfers better warm.