Multiple Tables in field Lookup method

public void lookup()

{
  Query                   query = new Query();
  QueryBuildDataSource    qbdsPurchTable,QbdsInvntQO, qbdsInventDim;
  QueryBuildRange         qbrVendId,qbrPurchStatus,qbrPurchType;
  QueryBuildLink          qblink1, QbLink2;
  SysTableLookup  sysTableLookup = sysTableLookup::newParameters
                                             (tableNum(PurchTable), this);
  ;//breakpoint;
  qbdsPurchTable = query.addDataSource(tableNum(PurchTable));
  QbdsInvntQO = qbdsPurchTable.addDataSource(tableNum(InventQuarantineOrder));
  QbdsInvntQO.relations(false);
  QbdsInvntQO.joinMode(JoinMode::NoExistsJoin);
  qblink1 =  QbdsInvntQO.addLink(FieldNum(PurchTable,PurchId),
                                 FieldNum(InventQuarantineOrder,TransRefId));
  qbdsInventDim = QbdsInvntQO.addDataSource(tableNum(InventDim));
  qbdsInventDim.relations(false);
  qbdsInventDim.joinMode(JoinMode::NoExistsJoin);
  QbLink2 = qbdsInventDim.addLink(FieldNum(InventQuarantineOrder,InventDimId),
                                               FieldNum(InventDim,InventDimId));
  qbdsPurchTable.addRange(fieldNum(PurchTable,                                                                OrderAccount)).value(PurchTable_InvoiceAccountGrid.valueStr());
  qbdsPurchTable.addRange(FieldNum(PurchTable, PurchStatus)).
                                          value("Invoiced,Received");
  QbdsInvntQO.addRange(fieldNum(InventQuarantineOrder,                                                     Status)).value(queryValue(InventQuarantineStatus::Ended));
  qbdsInventDim.addRange(fieldNum(InventDim, InventLocationId)).value("102018");
  sysTableLookup.addLookupfield(fieldNum(PurchTable,OrderAccount));
  sysTableLookup.addLookupfield(fieldNum(PurchTable,PurchId),true);
  sysTableLookup.addLookupfield(fieldNum(PurchTable,PurchStatus));
  sysTableLookup.parmQuery(query);
  sysTableLookup.performFormLookup();
}