The increasing use of Enterprise Social Networks (ESN) has been resulting in important changes in individual work practices, and is subject of numerous studies. From both a theoretical and a practical perspective, there is a lack of well-founded knowledge on how the implementation of ESN can be supported best to trigger both learning and change processes in the enterprise. For such processes, managers have a strong multiplying and "role model" effect. Therefore, following a case study approach, we conducted 15 interviews with managers at different hierarchical levels at a financial services provider to identify factors obstructing the successful ESN introduction and implementation. Understanding these obstructing factors is an important prerequisite for the competency development of both management and staff for a successful ESN implementation.