From looking at the logs my first suggestion would be to give a call over to your hardware vendor.

From the diag:

0500:0000:0000:0000  Device Name             "HARDWARE_FAILURE"
                     Primary Inquiry         "QUANTUM SCALAR50        0033"
                     Serial Number           "QUANTUM SCALAR50        QP0828BDC00246"
                     Device Flags            USCSI, SN(TYPE 0), SN(ELEMENT), NDMP
                     Device State            3, Online

                     Device IDs              1004, {F3B5072D-4D92-43B1-A388-9DF72B17C136}
                     Device Name             "QUANTUM 1"
                     Device Type             2131755008, "CHANGER FS=1"
                     Device Features         0x00006000: RMP,RRD
                     1st Slot Number         1
                     Number Of Slots         38
                     Portal Slots            0
                     Import/Export           Manual

                     Drive Element 0         1007, "MISSING DEVICE          MISSING_DRV_IN_LDR_90"
                     Drive Element 1         1006, "HP      Ultrium 4-SCSI  HU18322VGD"

-------------------  -------------------------------------------------------------------------------

0000:0000:0095:0001  Device Name             "HARDWARE_FAILURE"
                     Primary Inquiry         "MISSING DEVICE          CAGM"
                     Serial Number           "MISSING DEVICE          MISSING_DRV_IN_LDR_90"
                     Device Flags            USCSI, SN(TYPE 0)
                     Device State            3, Online

                     Device IDs              1007, {B98995C8-FEE2-4BF2-839C-03649A603988}
                     Device Name             "MISSING 1"
                     Device Type             0, "***"
                     Device Features         0x00020000: HU
                     Device Element          1004, 0
                     Device Block Limits     [512, 65536]

but the tape backup auto loader does not show any error and show that it is ok
only when detecting that time it show missing1
:(

Can you run a vxgather and ftp it up for me to review? Just select Backup Exec Base Logs.

http://seer.entsupport.symantec.com/docs/318474.htm

You can use anything for the case number. just let me know the number you use so I can find the file.

hi,

our side block ftp , how may i send the file securely over?

you will have to place it somewhere for me to download then.  private message me the link when you have it available.

 TILDBG.txt

Drive  ( 00,01,00 ) 01 is my tape drive which has gone missing thanks
Drive  ( 00,95,01 ) 90  MISSING DEVICE          CAGM  this phantom drive came up

From the logs you have posted so far it appears that either the devices are not terminated correctly or there is a problem with the communication on the hardware side of things.  I would really suggest giving a call over to your hardware vendor to have them look over the library.  Backup Exec is not generating any of those errors, it is only reporting them.

 it is backup an ndmp device, the setup was all connected via a cisco 9124 switch via fibre
the zone setting was zone 1 the backup exec server zone 2 the ndmp device and the robotic library,

did not know that at first and call up the hardware vendor which change the zone as the support person in symantec said that the tape device must be detected at the OS level first.

The NDMP is detecting the library is it?
backup exec only detect the NDMP device and does not detect the tape library

can i check how does the detection of the NDMP in version 12 as currently the robotic library is not shown at the NDMP device level, will be asking the hardware vendor to change back the configuration.

but previously one tpe drive was not detected and the backup was unable to run even with one tape drive alive

Maybe some network issue within as they change the infrastructure network

how can i check the ndmp device is nicely detected ?
i can see from the adamm log itself but how can i do a troubleshooting

i can telnet into the ndmp device port 10000 which is the port set which no issue and can add the NDMP device.

Any troubleshooting steps i should take to check the robotic library and the tape drives as the vendor say that the NDMP device do not need to know the robotic library.

I ask the hardware vendor to check the NDMP device and the data mover does show the tape drive.

hwo can i troubleshoot more into the issue as we have gone 2 weeks without backup and i am not able to backup the content in the backup exec 

Can you provide me the Symantec case number you recieved when you called in on this issue?

281-559-862

That case appears to be resolved as of today,  after the zoning was changed on the fibre.  Is this correct?

 yes