Access IIF function takes an expression and returns with whether it is true or if it is false.
The syntax that is used to determine whether the expression is true or false is:
Iif(expression, truepart, falsepart)
This function with go through both the truepart and the falsepart even though you will only get one answer. Knowing this, keep an eye out for possible errors that can occur. Sometimes it will return saying the expression is false when in fact it is true.