DPm Server 2012 errros on tape

Hi,

I have installed a HP LTO Ultruim-4 Drive as an standard alone drive. I have Two protection groups backing up to disk and tape. The disk part of DPM is a dream. The tape side keeping getting errors, on a Sunday morning we backup to tape

First Error : Failed to perform the operation since the tape is not available in a standard alone tape library Hewlett LTO ultruim-4 Drive(ID-24050)

Second Error: Failed to perform the operation since the free tape is not available in a standard alone tape library Hewlett LTO ultruim-4 Drive(ID-24050)

I have 4 tapes - Week 1 - Week 2 - Week 3 - Week4


Do we have a problem with the tape drive? Is like the back
up is not finishing from the previous week

regards,