Wazine and laying hens

[Yurd Ahd]

Hi I have given my hens wazine once a year for two years and they have been fine. I am confused because on here it often says wazine isn't for laying hens - why? is it bad for them or the eggs? We have always waited at least a week until we eat the eggs after dosing them. This year I decided to throw the eggs laid after the dose in the incubator just to see if they would hatch... nothing hatching yet and it's been over 23 days. Should I just chuck them or is a "wazine" chick possible? :b Thanks