Where did it go wrong?

These are my grape vines. They are beautiful too look at while sitting in my yard. But there's a problem! There's absolutely no grapes on them! There had been several weeks back. It was full of little clusters of grapes. I was so excited! About A week after I noticed all the clusters I went to look and there was nothing left but the leaves. Surely birds didn't get them all as it was loaded!! Any advise or clues as to what happened would be greatly appreciated. Thanks!

Posted using Partiko Android