Really, Communism does work, every day, even in this country... but only at the family level. One or two productive people share their resources so that everyone gets approximately the same benefits, and so that everyone's needs are met as well as they can be. They do it out of love.
However, when you try to use the force of government to force every citizen to show as much love for some ne'er-do-well 1000 miles away as they do for their own child, well, you're going to run into trouble. Then, when you turn over the entire resources of a nation to a central authority, the opportunity for massive displays of favoritism and corruption (and worse, usually) is inescapable.
But otherwise, it's a really, really nice idea! We should all share and play nice and want to help everyone get their needs met! Unfortunately for the Utopia-minded, in practice on larger scales, it's an abysmal failure, and will always be... unless you change human nature itself, including love, pride, self-interest, and that pesky little "power-corrupts" thing.
From each according to his ability, to each according to his need sounds eminently fair, until you realize that the Glorious Leader gets to decide what your needs are!