Often I cannot add something to my cart: although it is empty there appears a notice: The maximum quantity allowed for purchase is 1.:grrr:
Make sure that you are Logged into the store,
then add another product to your cart
Then edit your cart to remove this item, should just leave the original item.
If you are adding from your Wishlist, check to see if you have more than 1 item in the square on the wishlist. I get this message when I have inadvertently added the item more than once to my wishlist. I change it back to 1 and then it goes into the cart okay.
Thank you very much, chohole and AtticAnne!! It worked with your advices!