In this paper, we present the first phase of the LELIE project. A tool that detects business errors in technical documents such as procedures or requirements is introduced. The objective is to improve readability and to check for some elements of contents so that risks that could be entailed by misunderstandings or typos can be prevented. Based on a cognitive ergonomics analysis, we survey a number of frequently encountered types of errors and show how they can be detected using the discourse analysis platform. We show how errors can be annotated, give figures on error frequencies and analyze how technical writers perceive our system.