Hi,
Could be that it's trying to read a partial bar-code with that sticker on it. shirmal is correct in asking you to remove the stickers.
If what he suggests above doesn't work, check the usual hardware:
1. SCSI cable is securely connected to the server and the tape drive.
2. Any errors on the tape drive? If so, what are they?
3. Get hold of HP Library and Tape Tools (HP LTT) and run the diagnostics against the tape drive to eliminate any hardware issues.
Laters!