Opened eggs that didnt hatch!! Someone shed some light on why they didnt hatch? ***GRAPHIC PICTURES*

[chellebells]

13 eggs hatched on day 19/20. 6 eggs didnt hatch, didnt even internally pip (that i could see), so on day 23 i opened one up and this is what i found, any ideas anyone? gutted cuz it was my bought in silver laced wyandotte eggs that mainly didnt hatch, any thoughts would be eagarly recieved before i buy more eggs as i dont want this to happen again :-( thanks