I agree with Elder and a couple others that "communism" works on a small scale. We can look at several examples of "communes" that people shared their work and labor to benefit the group. I think the key to being successful is having a group of like minded individuals that all share that vision and goal and know the role that they will play in the big picture.
If we look to the example of the early Christians, they set up small groups that shared everything and would even sell off their possessions to get money to help out those who didn't have any.
I think the breakdown comes when it is forced onto people and groups do take advantage to keep the "common people" equal and set it up to give themselves an advantage, much like we have seen in the former Soviet Union and in China.
