Monitoring technology, especially sensor-based technology, is increasingly taken into use in care work. Despite the simplicity of these technologies – aimed to automate what appear as mundane monitoring tasks – recent research has identified major challenges primarily related to the technology's ability to meet the complexity of care work. Understanding intersectional challenges between these care technologies and care work is fundamental to improve design and use of health informatics. In this paper we present an analysis of interaction challenges between a wet-sensor at the task of monitoring wet beds at a nursing home. The analysis identifies the multifaceted nature of monitoring work and the intricacy of integrating sensor technology into the complex knowledge system of monitoring work.