User blog comment:Jarcellon/Build/@comment-5264386-20130410221822/@comment-5123071-20130411224843

If you haven't been able to backstab anything, you've probably been keeping your shield up. You cannot backstab while blocking.

Also you do actually do a bit more damage if you attack while the enemy is "staggered", so right after you block their attack, or after you kick them, or while they are dodging.