We have yet to see (real) Capitalism being used properly either.
That is the real problem. The real capitalism is not used anywhere. For example, in the US, it is Socialism being dished out after re branded as Capitalism.
That's the problem with all : socialism , communism , capitalism etc...In theory all sound ok. In real life , humans find a way to f*** it so good you need to invent a new concept.
There's no "new concept" that will fix that. The best thing is to take good parts from everything. Also, improve them slowly over time. But bottom line, human nature will always fuck great ideas up.
For example, REAL communism never happened. What happened in Russia, China, etc, was NOT communism. Communism in its supposed form is actually pretty damn amazing - think about, nobody wants for anything, everyone has the same quality of life. There's no need for conflict when we're all equal in terms of food, material goods, etc. But as a society right now, we are not ready for this kind of equality - not all of us want it, and there will always be people who want to abuse their power to live better than anyone else (which is exactly what the people in power in semi-communist states like USSR did). So even though communism is not that bad of an idea, human nature prevents real communism from ever taking place.
As for capitalism, for me the biggest problem is that once you get big, you become "too big to fail" which is a blatant contradiction of the entire concept. Failing systems should be allowed to fail, but we are supporting them. The people that get to the top of the capitalist ladder tend to stay there (if not indefinitely, at least for much longer than they should) and amass ridiculous amounts of power to control the entire system.