I have incubated three batches of eggs. I have read up on temps, humidity and everything! Everytime I do my lockdown on day 18, I get one or two hatched on day 19, maybe another on day 20. Then NOTHING. I have cracked the eggs after day 25 passes and almost every egg has a fully developed chick that just did not hatch!!! Does anyone have any advice? I am so discouraged and I feel so guilty!