This paper deals with writing a proof text as the final step of the proving process at university level, particularly when it results in a disorganized, unclear draft. The reported study concerns third year university students when dealing with proof tasks for which the proving process has to be built up, as opposed to tasks that students may tackle by known proving procedures. By comparing the analysis of students' proof texts with their interview responses, a strong influence of the didactic contract, lack of meta-knowledge about proof, and a weak mastery of concepts were identified as possible reasons for the poor quality of the proof texts. Some educational implications and hints for further research are provided.