Employees don't work well together
In our private lives we surround ourselves with people with whom we are in direct harmony. Usually we also find it easy to communicate with our environment. In our daily work, people meet and need to get along with each other - it's not just about language, it's about human interaction.
Managers need to be able to work well with their employees. They also need to be able to solve problems that arise between different employees or groups. Finally, managers must apply the basic principles of good work relations, so that problems of poor cooperation are avoided preventively.