Diagnosis
You have set a structured field as a data dictionary reference.However, from the point of view of generic attributes this makes nosense, as the structure cannot be used internally.

System Response
Internally, the system uses the reference to the field HRT1222-LOW. Theattribute is therefore treated as if it were untyped. No input oroutput conversion is possible.

Procedure
To define the attribute correctly, use a field from a flat structure.
You can only define invisible attributes in this way.