Ax 2009 Lookup method

Hi everyone.İ have a question.İ have a lookup method like this.İ want to add a field (CompanyInfo.VatNum).But i dont know how can add this column.Anyone help me?

public static void lookupDataAreaName(FormControl _formControl)

{

Query query = new Query();

QueryBuildDataSource queryBuildDataSource;

QueryBuildDataSource qbds;

SysTableLookup sysTableLookup;

;

query.addDataSource(tablenum(DataArea));

sysTableLookup = SysTableLookup::newParameters(tablenum(DataArea), _formControl);

sysTableLookup.addLookupfield(fieldnum(DataArea, id),true);

sysTableLookup.addLookupfield(fieldnum(DataArea, name));

sysTableLookup.parmQuery(query);

sysTableLookup.performFormLookup();

}

This is my lookup.İ want to add CompanyInfo.vatNum.How can i add this?

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