Why was the gran chaco war a failure for the league of nations?

Neither Paraguay nor Bolivia where or are industralized nations, so it is imposible for them to go to war unless other nations provided the weapons for the fight. I have read that this war was fougth with the most moder weapons of the time. All of them in Bolivias side off course, until they were captured by the paraguayans. Paraguay could no by the weapons because the Leage of Nations put an embargo on Paraguay, and send them to war unarmend. So the liague of nations wanted Bolivia to take the Chaco from Paraguay and fail.