Form LookUps in AX 2012

Lookup on Strning control:

public void lookup()
{
    Query                   query = new Query();
    QueryBuildDataSource    queryBuildDataSource;
    QueryBuildRange         queryBuildRange;
    SysTableLookup          sysTableLookup = SysTableLookup::newParameters(tableNum(custTable), this); 
    
    sysTableLookup.addLookupField(fieldNum(CustTable, AccountNum));
    sysTableLookup.addLookupField(fieldNum(CustTable, CustGroup));
    
    queryBuildDataSource = query.addDataSource(tableNum(CustTable));
    queryBuildRange = queryBuildDataSource.addRange(fieldNum(CustTable, CustGroup));
    queryBuildRange.value('40');

    sysTableLookup.parmQuery(query);
    sysTableLookup.performFormLookup();
    //super()
}

Lookup on RefereceGroup control:

public Common lookupReference(FormReferenceControl _formReferenceControl)

{

        //Common ret;
        //ret = super(_formReferenceControl);
        //return ret;
        HcmWorker worker;
        Query lookupQuery;
        SysReferenceTableLookup sysTableLookup = SysReferenceTableLookup::newParameters(tableNum(HcmWorker), _formReferenceControl, true);
        sysTableLookup.addLookupMethod("Name"); 
        sysTableLookup.addLookupfield(fieldNum(HcmWorker, PersonnelNumber));
        lookupQuery = new Query();
        lookupQuery.addDataSource(tableNum(HcmWorker)); 
        sysTableLookup.parmQuery(lookupQuery);
        worker = sysTableLookup.performFormLookup();
        return worker;

 }