Technically the compromise did last... during that time. It kept the balance of power between slave states and free states. There were multiple compromises after the Missouri compromise, and each of those compromises were a temporary solution because the United States was growing. But eventually as tension between the North and South grew greater then the Civil War broke out.
Long Answer short the Missouri compromise was like a band-aid being put over a bullet hole.
I'm pretty sure I'm right, if i'm not. Sorry :)
