Custom Lookup in Ax

public void lookup(FormControl _formControl, str _filterStr)
{
sysTableLookup sysTableLookup;
Query query = New Query();
QueryBuildDataSource qbdsJour, qbdsTrans,qdbsVend;
QueryBuildRange qbr;
;
sysTableLookup = SysTableLookup::newParameters(tableNum(VendPackingSlipJour), _formControl);
qbdsJour = query.addDataSource(tableNum(VendPackingSlipJour));
qbdsTrans = qbdsJour.addDataSource(tableNum(VendPackingSlipTrans));

qbdsJour.relations(true);
qbr = qbdsTrans.addRange(fieldNum(VendPackingSlipTrans, ItemId));
qbr.value(<ItemId>);
qbdsTrans.relations(true);
sysTableLookup.addLookupfield(fieldNum(VendPackingSlipJour, GRNNumber_IN));
sysTableLookup.addLookupfield(fieldNum(VendPackingSlipJour, PurchId));
sysTableLookup.addLookupfield(fieldNum(VendPackingSlipJour, OrderAccount));
sysTableLookup.parmQuery(query);
sysTableLookup.performFormLookup();

}