Aloe vera is a good natural remedy for burns and it works well for sunburn, but if you have bottled aloe vera gel or lotion leftover from last year, it may be worthless. It loses a definite amount of effectiveness over time. The fresher it is, the better it works.
Use real aloe vera. Buy a plant and keep it on your kitchen windowsill. It grows easily and it’s always there when you need it. Just cut off a “leaf” or spear, split it and rub it all over your sunburn. It’s really soothing and it helps heal your skin. The plant grows back quickly.