I had a lot of problems with bacteria and drowning with my last batch of ducks. I suggest cleaning out the incubator thoroughly that you are using, and maybe sanitize the hatching eggs if they are obviously dirty. If its not bacteria maybe the breeder stock has a deficiency? Other than that im...
Call ducks are notoriously hard to hatch and often need assistance due to their short necks and bills. What is the humidity in your incubator at hatch?