The following are problems of development planning in Nigeria EXCEPT

Nigeria, like many developing countries, faces several challenges in its development planning. These include issues such as inadequate capital, which limits the ability to fund critical development projects and infrastructure, thus hindering economic growth. Another significant challenge is the inadequate statistical data, which affects the ability to make informed, evidence-based policy decisions. Without reliable data, it's difficult to plan effectively and measure progress.

Poor implementation of economic planning is also a notable problem, as even the best-laid plans cannot yield results if not properly executed. This might be due to bureaucratic inefficiencies, corruption, or lack of capacity.

However, the statement under-population is not a commonly recognized problem in Nigeria. In fact, Nigeria is known for having a large and rapidly growing population, which sometimes poses its own challenges in terms of resource management and service provision. Therefore, the issue of under-population can be seen as an exception to the typical problems of development planning in Nigeria.