Symantec Backup Exec 12.5 cannot back up tape?

[safa]

Dear All,

syntomps :
1. Media Tape out automatically when running back up
2. Cleaning Media Tape did not recognize by BX910 S1
3. Blade 4 (BX920) connect to BX910 S1.
4. Server Blade OS Type on Blade 4 : Windows Server 2003 R2 Enterprise Edition
5. Aplication Symantec Backup Exec 12.5
6. Backup process always failed and the tape media always come out

Why i cannot running backup tape, media tape always out when i running backup??

Thanks