Diagnosis
You have assigned the variable key of a subfeature to a main feature.This assignment follows a decision operation in which the field nameis not marked in the main feature structure and is thus not permissiblein this branch of the tree.

Procedure
Since the field name is not permissible for the main feature, thetree branch for the subfeature is cut off when a decision operationwith this field name occurs. All assignments beneath this are thusinvalid. You must either delete the assignment or mark the fieldname in the main feature structure.