After 20 or so eggs laid by the serama hen that are infertile, finally I have 3 eggs that are fertile. I don't really know the reason why the roo can't do his job properly, but that's ok with me as I'm not into breeding this type of chicken. I only keep them as pets and if they happens to have chicks, I might raise them up and give away to my friends who ever want them.
Here is a pic of fertile egg at about 8 days old in the incubation. You can see few blood vessels are forming and tiny chick at the middle right.