Thrown when familySymbolId is the id of some element that is not a FamilySymbol, is not of the category “Connection Symbols” (OST_StructConnectionSymbols), or has its “Apply To” parameter not equal to this type’s applyTo property.
The FamilySymbol must be of category “Connection Symbols” (OST_StructConnectionSymbols) and have its “Apply To” parameter set to match the applyTo property.