This stage is always a stressful time.

Had you candled at all during incubation? Sometimes eggs don't develop or stop early on for various reasons. Shipped eggs can get damaged internally on their way to you and it's common for them to stop developing in the first week. If you leave them in the incubator the bloodring fades and they can look like they never developed.
If they look full and dark that's a good sign. Sometimes you can see them pushing at the air cell. I find that dead chicks look very black and lumpy and there's often a watery layer between it and the bottom of the air cell with no veins visible. A live egg has a reddish glow to it. I use two light sources when candling my eggs - one behind and one on the fat end where the air cell is. The colour of the shell can make it very difficult to see inside.
Sometimes eggs can take up to 25 days to hatch out so there's still hope for your eggs and the fact that two were full and dark is a very good sign.