Once you have a proven pair of Angels they will spawn aprox every 2 weeks. Sometimes two females will spawn together. So that is a possibility too.
What did they deposite thier eggs on ( ei leaf rock filter tube ect.)
Angels will eat their spawn if spooked to much or stressed to much. Some parents will always just eat them too. If you want the parents to raise them then there are a few things you can try if they keep eating the eggs .
here a link to Angels plus go to it then click on the link in the all about Angels section then the breeding Angels link There is lots of info there it is about half way down on the left hand side of the screen
http://www.angelsplus.com/
Good Luck