Scan is a read operation
Format and Backup are Write operations
Your tape drive is able to REad, but is not able to write to the media. The error message reflects that, as well as the error in Library and Tape Tools
If the device were attached to a UNIX-based system, I would have you test outside of DP using the 'tar' command
My suspicion is that either you have a cabling problem, or it is not terminated correctly, or, most likely, the tape drive is bad, and needs replacing