What Gridley said, basically the UN is very, very squeamish about doing things that involve coercion, only the Security Council can make binding resolutions.
The glory of the United Nations isn't that it's a world police organization but that it provides a forum for nations to resolve disputes and attempts to do so in the most fair and balanced manner possible, does it have a whole string of failures? You bet your ass it does, but then again imagine half the shit they have to deal with EVERY DAY in that organization.
The UN technically has all of zero authority on a particular matter unless the international community decides as a whole to give it such, it didn't just roll into East Timor one day and decide to help it transition to independence from being a very, very unwilling part of Indonesia, it had to be voted the authority to transition East Timor into Timor-Leste. The UN still fails to significantly affect the outcome of multiple issues today because people don't approve of it, that's why you see the African Union holding down the fort in Sudan as best it can and not a huge UN peacekeeping brigade, China's going to veto that shit if they try.