Even though thsi forum is for the full Data Protector product, I checked for support matrices for Data Protector Express. The latest version is 6.0. It does not appear that this version supplies support for W 2012 R/2
http://h20565.www2.hp.com/portal/site/hpsc/public/psi/swdHome/?lang=en&cc=us&sp4ts.oid=5171306
There is also a PDF document, I was not able to copy the link, you would need to 'google'
data protector express support matrix
I am also noy understanding your device address \\.\tape0
Usually, it is in the format of a Windows SCSI path, for example
Tape2:0:1:0C
or a UNIX device file, for example on HPUX
/dev/rmt/c2t0d0BESTn
So, the problem may be in how it was configured. You can get the correct tape path by running, from the command prompt
Windows
cd \Program Files\Omniback\bin
devbra -dev
UNIX
/opt/omni/lbin/devbra -dev