Particularly in a B2B context and especially at the enterprise level, new product sales and adoption encounter a world of organizational dynamics, dysfunctions, disparate priorities, funding streams, and basic inertia that often are what actually creates the need for your product but also undercuts demand.
My first startup created a mobile communication tool for both the education and the healthcare sectors at different times. In both, there was a clear and acknowledged communication problem - in education among schools and students, and in healthcare among administration and physicians. In each sector, we found a solid early interest in our solution.
Both sectors, however, are also highly regulated and compliance driven. Both sectors are risk averse and bureaucratic. Both sectors have complex decision-making structures and resource allocation processes. And, both sectors are notorious for culture problems among administration, front-line staff, and the people they actually serve. This is why both sectors have severe communication problems (need), and also why both sectors have not been able to commit to solving (demand) their communication problems.
Needing a communication solution and demanding one are two different things. Our startup got a lot of head nodding and early interest and affirmation, but was never able to scale our sales to match.
In hindsight, we had achieved problem/solution fit (need oriented), but a couple of years later we were still searching for product/market fit (demand oriented).