Running Arcserve 11.5 last few days our nightly backup will not start gives error message to mount blank media or any not belonging to media pool. We are currently using a five day rotation of dlt tapes and have not had a problem up until 2 days ago. Any ideas of what could of happened, our DLT drive seems to be working properly, i'm thinking it is a software setting in Arcserve any suggestions on where to begin? Thanks.