I want to use the "IF" function to allocate students to groups based on their
date of birth. I have tried doing this using the format

IF(D2<1/9/1994,"Secondary","Primary")

D2 is the cell with the first student's date of birth. I can't get the
result I want, as all students come out as "primary" regardless of their date
of birth, and even the first student was born in 1989.

Can anybody help?