Netbackup make tape drives to go down

HI,

Would like to know why netbackup keep my drives down when it founds the WRITE PROTECTED media. We have several other non write protetced medias available in the libray but it's not using it.

Error write error on media id HFE082, drive index 6, writing header block, 19
Error TapeAlert Code: 0x09, Type: Critical, Flag: WRITE PROTECT, from drive ukyorm0015_000_TLD_2 (index 6), Media Id HFE082
Error write error on media id HFE081, drive index 3, writing header block, 19
Error TapeAlert Code: 0x09, Type: Critical, Flag: WRITE PROTECT, from drive ukyorm0015_000_TLD_3 (index 3), Media Id HFE081
Error write error on media id HFE081, drive index 3, writing header block, 19
Error TapeAlert Code: 0x09, Type: Critical, Flag: WRITE PROTECT, from drive ukyorm0015_000_TLD_3 (index 3), Media Id HFE081
 

All my 2 drives went down after this error, why can't it go ahead and use the good medias?