A job that runs on multiple tapes stuck at one tape

Hi I have a backup job that runs on multiple tapes, but when i run it , after filling the first tape , it couldn't auto-load the second tape.  I use HP 1x8 G2 Autloader and symantec backup exec 2010 R3, 

For media changer on the device manager, it uses unknown media changer ( the Microsoft one)  but I don't think the problem have something to do with robotic library because i runs a job normally ( as in doing so it automatically pick one tape from the tapes on magazines) and the inventory also works fine.

I use a media set, i have created and have associated  all the tapes with it, and i can see all the tapes are on the Online Media.

Do you have any idea what could be the problem?