Restore Issue On LTO-4 Ultrium RW data cartridge

HI,

I have One tape & monthly taking normal backup of my files.Today i am trying to take backup i got a message that media full insert the new media or press cancel the current job....So i press cancel..

Now I want restore the previous back up files..when i insert the tap i am getting below image error

OS : Windows 2003 Server : LTO-4 Ultrium RW data cartridge.

Thank you all...