Back more than any other bdpt requires a special kind of mind-muscle connection. If not, your biceps will be getting a great workout, but not your back. I remember reading in a mag long ago as a teen, that when doing any type of chin, pull down or row, to think of your hands & arms merely as "hooks", and you pull those hooks with your lat muscles. It takes a little practice to get down pat, but when you do, you will know it, as your lats will pump quick & you will start growing.
Here's another little trick that can help. Start your back workout with pullovers. Nautilus pullover machine is best, but not many gyms have them these days. So if you don't have access to one, then do db pullovers instead. Do them with your body laying across the bench - as in perpendicular, not parallel. Do a warm up set or 2, then 2 bust ass sets to failure - 10-12 reps each set. What pullovers do is something no chin, pull down or row can - it doesn't use any biceps at all. So you are pre-exhausting your lats, so you should feel it more in the lats when you move on to your following lat exercises.
With the solid advice given from Myo & Dark, I think if you combine all these techniques, you will start to see results. Also remember what Myo said about volume - intensity trumps volume all day long. If you truly bust ass on every rep & set, you will NOT be able to perform much volume bcoz you will be spent. Good luck.