Mine don't either.. Mine prefer and flake that makes it to the bottom, catfish pellets, and love a bit of bloodworm.. Its like watching a little fella with a mansize spaghetti....
Don't worry mine ignore them as well, even though there is a pic of my species on the box! again mine go for the left over flake, sinking pelletts and bloodworms
corys are omnivorous, and take in most of their vitamins from invisible decomposed plant material in the water, which is why they don't go for algae wafers.
Yeah, mine really like Hikari algae wafers too. Actually they like just about anything Hikari makes. I put the whole wafer in the tank and all of them will crowd around it and push it around the tank.
Maybe I missed this, but what kind of cories did you say you had?