With the Tape alert flag that is given it states that the tape in slot 36 is a cleaning tape. Now the cleaning tape should clean your drive unless it is expired and then it will need to be replaced. Also is slot 36 marked as your cleaning slot? If it is not then you will want to make sure that it is marked as your cleaning slot for both the TL4000 & in Netbackup so that it won’t grab the tape & try to use it to backup data on it.
Please let us know if you have any other questions.