Child labor is not an easy issue to resolve; while it seems noble to immediately withdraw investments and cooperation with firms and factories that employ child labor it may do more harm than good. Many of these children are from very poor families and work to pay for their family and/or their education. Depriving them of this income has led to some children seeking different, lower paid work, and even prostitution in some cases. Other ways with schemes to help children would likely be needed so that this labor can be phased out. The same has been suggested by the International Labor Organization (ILO), at a meeting in Mexico City in 1999, who also pointed out that child labor affects over 250 million children, 30 percent of which are in Latin America. A gradual phase out is said to be a more preferable solution.
According to the UK Committee for UNICEF, poverty is the most common factor contributing to child labor. In addition, "debt, bloated military budgets and structural adjustment programmes imposed by the International Monetary Fund and the World Bank, have eroded the capacity of many governments to provide education and services for children, and have also pushed up prices for basic necessities". (For more information on these aspects, also see this site's section on causes of poverty and the harmful structural adjustment policies.)
According to UNICEF, Somalia and USA are the only two countries in the world that have not ratified the United Nation's Convention on the Rights of the Child. The convention is the world's most widely ratified treaty. (USA have signed it, but Somalia has neither signed, nor ratified it, at the time I write this -- and Somalia doesn't currently have an internationally recognized government, which is why they cannot ratify the convention. The US have no such excuse.)