If you are using Internet Explorer from your cell phone then ignore the above advice and download Firefox app. I went through the same thing for a month and all this ^ advice is all anyone could recommend. Firefox takes up alot of bandwidth so I only switch to it to upload a picture.
You don't need to switch to desktop mode and I know that people are trying to help but it gets old having them walk you through where the upload button is. We can see the button, it just doesn't work for IE.