If you don’t clearly communicate your expectations to your project team and stakeholders you will never have those expectations met. You must define standards for communication and performance and let your team know as early as possible what those expectations are. You must state your expectations to stakeholders explicitly and hold them accountable to those expectations.
In the absence of clear expectations teams and stakeholders will make assumptions about how they are to proceed. You, the project manager, must then compensate for any incorrect or conflicting assumptions which dilutes your effectiveness in managing the project.