Hello,
I must be tired, but cannot see what is wrong with this formula.
=IF(OR(MONTH([Planned Entry Date]@row) = 1, MONTH([Planned Exit Date]@row) = 1), "Jan", "Notok")
if either of the 2 dates. are filled, result is Jan
if none or just one is filled, result is #INVALID DATA TYPE
Thanks a lot
Raoul