In October 1935, Mussolini began his invasion of Abyssinia. This was a clear-cut case as it was a large country invading a smaller one, and the League was ideally placed to act. A committee was immediately set up to agree what sanctions to impose, but a decision was delayed for 2 months as it feared America wouldn't support the sanctions. It was also due to the fact that League members' economies would be damaged further.
The Suez Canal, Italy's main supply route to Abyssinia which was owned by Britain + France, was not closed off as they feared it would start a war.
There was secret talks between France and Britain about how, if they said to Italy that if they called off the invasion, they would get 2/5 of Abyssinia. This was leaked to the French Press, but it was too late by then as Italy had already taken too much of Abyssinia.
When Hitler marched into the Rhineland in March 1936, the hopes of France being for sanctions against Italy vanished as they were more bothered about Germany. In May, Mussolini had completely annexed the country as the League watched on helplessly.