This paper deals with the writing of a proof text as the final step of the proving process. In particular, students' difficulties to get a satisfactory product, which frequently result in an unclear text in a disorganised form, are analysed. Differently from other difficulties related to proof and proving, we noticed this phenomenon particularly when third year university students were answering some open questions where the process has to be built up, differently from traditional questions of calculation or direct use of a mathematical result where the steps of the process are known, regardless the correctness of the proof. We'll try to identify the reasons behind writing an unclear, messy draft instead of a clear readable proof text; its consequences on students' making proofs at the university level will be considered.