Why didn't the 1919 league of nations really work out?

The 1919 League of Nations was the first diplomatic organization which had as main goal to maintain peace, promote international cooperation and prevent another world war from happening, it was created after Word War I and failed it's purpose and dissolved with World War II.

The League of Nations failed mostly because of the absence of powerful nations such as United State, it was dominated by England and France which were imperialist nations that wanted to spread their empire and some nations like Germany and the Soviet Union were not allowed to join.  Another cause of its failure was its structure, it required unanimous votes for taking actions, which made very difficult to achieve goals and when countries attacked each other the League of Nations couldn't do anything about it because it lacked it's own army. The League of Nations had to uphold the Treaty of Versailles which placed Germany as the country who lost the World War I, which made the League of Nations seem not neutral, and Germans didn't respect it.

The League of Nations was dissolved and replaced with the United Nations after World War II.