If the sex-link is crossed incorrectly it doesn't work. You will end up with the same colours, but some of each colour will be male and some female. That is one possibility.
The other is that the farm store had the chicks marked incorrectly or that a bird from one brooder got moved to another.
The other is that the farm store had the chicks marked incorrectly or that a bird from one brooder got moved to another.