You can include multiple single-level or multiple nested functions in different output ports in an Aggregator transformation. However, you cannot include both single-level and nested functions in an Aggregator transformation. Therefore, if an Aggregator transformation contains a single-level function in any output port, you cannot use a nested function in any other port in that transformation. When you include single-level and nested functions in the same Aggregator transformation, the Designer marks the mapping or mapplet invalid. If you need to create both single-level and nested functions, create separate Aggregator transformations.