BE 2012 Compression ratio

Hi All,

I am using HP LTO-3 Ultrium 800 as my backup media. Under storage, the media storage capacity is 391GB and compression ratio is 1.0:1

How do i make it 2.0:1 for ratio?

FYI: I enabled compression and encrpytion for my backup job and now it reported no enough space.. my last backup byte count was 468GB.

Please help