Diagnosis
Substructures can only be included in other structures.

Procedure
If you still want to use the structure in your substructure, convertthe link to the substructure to an include.
Proceed as follows:
Note down the technical name of the substructure.
Remove the link to the substructure from your structure.
Position the cursor on the substructure.
Choose Info object -> Remove from structure.
Include the substructure.
Position the cursor at the location where the substructure should beinserted.
Choose Info object -> Insert -> At same level/assubnode.
The Insert Info Object dialog box appears.
Choose Use existing info object.
Mark Structure in the Info Object Class dialog box.
The Find Info Object dialog box appears.
Enter the technical name of the substructure and start the search.
Select the substructure and copy the selection.
The Structure dialog box appears.
Select Include.
The substructure is included in your structure.