Add to Cart intermitent
I have a product page linked to a database. There are about 20 items on the page. When I click on an "Add To Cart" button, sometimes it adds it to the cart and sometimes it doesn't.
It always goes to the cart page, but it doesn't always update the cart page. Ie. it either doesn't add a new item or update the quantity field for an existing item. I cannot figure out any pattern of when it works and when it doesn't. After clicking on Continue Shopping, if I refresh the product page a couple of times, the next Add to Cart that I select works, but not always.
What can cause this intermitent problem? How can I fix it?