they need a wet and dry season, if i remember. you need to kinda recreate the amazon year and the changes that takes place in it, like food shortages, etc.
that site, corydora world has a great breeding article, but i can't find the site, it used to be on the top, it's a MFT sponser...
idk, mabey i am mistaken? they might be easier to breed than that.
mabey try a search for "corydora world" and you might find it.
good luck.