Integrating multiple representations into a coherent mental model is one of the challenges when learning with multimedia. In this experimental study (N = 173), we examined how highlighting corresponding information in text-graph learning material can help higher education students to make the necessary connections and improve learning outcomes in two domains. We compared a control condition to a signaling condition with given highlights and an active signaling condition where students were asked to visually highlight corresponding text and graph information themselves. There was no overall benefit of given signals or active signaling. We discuss prior knowledge and the quality of learner-generated signals as possible explanations. For biology learning material, prior knowledge moderated the effect of active signaling. In economics, the effect of prior knowledge was mediated by the quality of learner-generated correspondences. Our findings suggest that different methods of supporting text-graph integration might be useful for different students and learning material.