There are certain Populations you will not be able to create, these are largely negative cases. For Example looking for all of the people who didn’t do an event. We consider these cases too generalized, you will need to add a positive condition so you can run your populations.

AND operator, and ALL of its operands are negative.

You cannot create a population in which all operands are negative, this includes:

Has Not Done Event

Does not have Property

To use the population you will have to use at least one positive operand.

OR operator, and has negative operands

If you use an OR operator - it is like each OR condition is its own independent condition, so each OR condition will be subject to the rule above. If you use the OR operator you cannot use a negative operand.

 Has Done

          AND

 Has Not Done

Frequency of Occurrences

You cannot set an Event Occurrence to Zero if it is the only step condition of the population.

You cannot Occurrence to:

At Least 0 times

At Most 0 times

Or Exactly 0 times