private void SetFormula(Document familyDoc) { _type = familyDoc.FamilyManager.NewType(_name); string newParamName = "Program Area"; // //familyDoc.FamilyManager.AddParameter("Area", BuiltInParameterGroup.PG_CONSTRAINTS, ParameterType.Area, true); // replaced by line below ParameterBinding paramBind = new ParameterBinding(familyDoc, "Areas", newParamName); // //FamilyParameter param = familyDoc.FamilyManager.get_Parameter("Area"); // replaced by line below FamilyParameter param = familyDoc.FamilyManager.get_Parameter(newParamName); if (null != param) { familyDoc.FamilyManager.Set(param, _area); } param = familyDoc.FamilyManager.get_Parameter("Height"); if (null != param) { // familyDoc.FamilyManager.SetFormula(param, @"Area / Width"); familyDoc.FamilyManager.SetFormula(param, @"Program Area / Width"); } }