Why wont my eggs hatch in the incubator

[claireree]

My partner made me a incubator which is working fine (made same one before and 100% success rate hatching snakes). The temperature is fine and the humidity seems to be staying at a steady rate of between 50 - 60% but none of my eggs seems to grow. I got once to the point one of my silkies was going to hatch and a problem with the electricity meant the incubator was turned off for a few hours and hence the chick died.

I currently have 2 bantam eggs and 11 duck eggs in the incubator as the duck abandoned the nest. I candled them a few days ago and at least a couple of them you could see veins forming but for some reason in the past this is as far as my eggs go they dont seem to go much further,

Please can you help, for me this is now getting a obsession I really want to know where I might be going wrong so I can prevent this from happening again

 

[claireree]

 

[One Chick Two]

If the temp and humidity seems perfect, could you get your hands on someone else's fertile eggs and do a test hatch? Or get some refrigerated fertile eggs from Trader Joes if you had to? Were your eggs old? I still want to think something is not quite right with the incubator situation- are you turning your eggs a few times daily? Are you placing them inside round side up? Hopefully someone else may have more ideas for you...

 

[GAQuail]

Are you sure your thermometer is reading accurately?

 

[bahamabanty]

I gave up on home made incubators after 3 failed attempts. I bought a brinsea mini eco for $75, and its the best 75 I have ever spend, I am on to my second hatch.