Cameroon only had independence for 50 years, which is as much experience as they have in running two nation-states (later became one).  When people look at the developing world, they see what is going on but rarely its history.  Prosperity happens gradually through an osmosis of many factors, and you have to start somewhere.  The level of social stability Cameroon is able to achieve within only 50 years is fairly impressive for a western African country, or any country for that matter.