'Grapes' in the Bible

He dug it up, gathered out its stones, planted it with the choicest vine, built a tower in its midst, and also cut out a winepress therein. He looked for it to yield grapes, but it yielded wild grapes.

What could have been done more to my vineyard, that I have not done in it? Why, when I looked for it to yield grapes, did it yield wild grapes?