Expression Builder Problem

[brainboxj]

I am trying to write a validation rule which needs to use a "then" expression but i am not skilled and i do not know how to do this.
i want to have two fields "Date given" and "Date collected" and one check box "collected? "

if "date given" is not an empty field and "date collected" is an empty field then i want "collected? " to be false (unchecked) or an error message comes up

if the "date given" is not an empty field and "date collected" is not an empty field then i want "collected? " to be true(checked) or an error message comes up

i think you may need to use the iif function but i need help.

[NeoPa]

You haven't described all situations here. What if [Date Given] is empty?