Review the following rules when you map nodes in the operation output hierarchy to output ports:
The operation output node and the output port must have compatible datatypes.
You cannot map a node to more than one output port in a group.
Each output port must have a valid location, unless the port is a pass-through port.
If you drag a multiple-occurring child node to an empty output port, you must relate the group to other output groups. When you select a group, the Developer tool creates keys to relate the groups.
When you drag a multiple-occurring element into a group that contains the parent element, you can configure the number of child element occurrences to include. Or, you can replace the parent group with the multiple-occurring child group in the transformation output.