PDR1908S
<FIELD> fieldname1 must have a reference point because it is referenced by <FIELD> fieldname2. Add a <REFERENCE>tag to fieldname1 or do not name it in a <FIELDREF> tag.
What happened: You defined a field that used another field as a reference, but the referenced field has no reference point. Any field named in a <FIELDREF> tag must be defined with a reference point. fieldname1 identifies the referenced field, and fieldname2 identifies the new field.
What to do: Make sure the Field group of the referenced field contains a properly defined <REFERENCE> tag or do not reference it from the new field.