Having completed the requirements engineering phase in a software engineering project, we usually refer to requirements as unambiguous, comprehensible and objective. In a software development case study conducted over a period of more than three years we observed several problems within and between the project teams resulting from different understandings of the software specification. Aim of the project was the implementation of a DWH that collects and evaluates significant data of an international banking institute in order to fulfill the requirements specified by Basel II. In order to classify and explain the observed communication defects that occurred during the implementation phase, we consider findings from communication theory and knowledge transfer (on the interaction setting). As a result, we propose a general schema for the classification of communication defects that may make a significant contribution to the handling of problems in communication issues.