yea darm, it seems that your dk is pretty undergeared for tanking effectively. Might i suggest getting in on a couple pug runs of heroics for tank gear. Gear up your tank solo for a bit, as this helped with my team quite a bit. check out the tank info at elitistjerks.com in the dk info, there's a "pre raid" gear list for gearing up to start raiding. Try to pick a couple instances that have upgrades, and just run them solo and try to get the items you need, gem and enchant em up and then go back and try with your box toons after you get a few more upgrades good luck!