Chain of command doesn't work on Data Provider

Question

I am trying to extend FreeTextInvoiceDP to add new fields to the report, I have created a chain of command, but when I run it the process does not go through the extension. I have debug it and effectively the extension doesn't work, is there anything that I have forgotten?

my extension:

 [ExtensionOf(classStr(FreeTextInvoiceDP))]
 final class FreeTextInvoiceDP_Cls_ARQ_CONCCo_Extension
 {
    protected void populateFreeTextInvoiceHeaderFooterTmp(CustInvoiceJour _custInvoiceJour, 
    CompanyInfo _companyInfo)
    {
    CustInvoiceTable    custInvoiceTable;
    CustInvoiceTrans    custInvoiceTrans;
    CustTable           custTable;
    TaxTrans            taxTrans;

    next populateFreeTextInvoiceHeaderFooterTmp(_custInvoiceJour, _companyInfo);

    custInvoiceTable = _custInvoiceJour.custInvoiceTable();
    custTable = CustTable::find(_custInvoiceJour.OrderAccount);

    freeTextInvoiceHeaderFooterTmp.ARQ_CONCCo_InvoiceId     = custInvoiceTable.InvoiceId;
    freeTextInvoiceHeaderFooterTmp.ARQ_CONCCo_InvoiceDate   = custInvoiceTable.InvoiceDate;
    freeTextInvoiceHeaderFooterTmp.ARQ_CONCCo_DueDate       = custInvoiceTable.DueDate;
    freeTextInvoiceHeaderFooterTmp.ARQ_CONCCo_Currency      = custInvoiceTable.CurrencyCode;
    freeTextInvoiceHeaderFooterTmp.ARQ_CONCCo_Address       = DirParty::primaryPostalAddress(custTable.party).address;
    freeTextInvoiceHeaderFooterTmp.ARQ_CONCCo_VatNum        = custInvoiceTable.VatNum;
    freeTextInvoiceHeaderFooterTmp.ARQ_CONCCo_CustName      = custInvoiceTable.Name;
freeTextInvoiceHeaderFooterTmp.ARQ_CONCCo_CompanyLogo   = CompanyImage::FindByRecord(CompanyInfo::find()).Image;
}

protected void populateFreeTextInvoiceTmp(CustInvoiceJour _custInvoiceJour, CustInvoiceTrans _custInvoiceTrans, TaxSpec _taxSpec, CustPaymSchedLine _custPaymSchedLine, CustTrans _prepaymentCustTrans, TaxTrans _prepaymentTaxTrans)
{
    TaxTrans    taxTrans;

    next populateFreeTextInvoiceTmp(_custInvoiceJour, _custInvoiceTrans, _taxSpec, _custPaymSchedLine, _prepaymentCustTrans, _prepaymentTaxTrans);

    select firstonly taxTrans
        where taxTrans.SourceRecId == _custInvoiceTrans.RecId
        && taxTrans.SourceTableId == _custInvoiceTrans.TableId;

    freeTextInvoiceTmp.ARQ_CONCCo_TaxCode = taxTrans.TaxCode;
}

protected void insertIntoFreeTextInvoiceHeaderFooterTmp(CustInvoiceJour _custInvoiceJour, CompanyInfo _companyInfo)
{
TaxTrans        taxTrans;
CustInvoiceTrans    custInvoiceTrans;

next insertIntoFreeTextInvoiceHeaderFooterTmp(_custInvoiceJour, _companyInfo);  

while select custInvoiceTrans
        where custInvoiceTrans.InvoiceId == _custInvoiceJour.InvoiceId
    join sum(TaxBaseAmount), sum(TaxAmount), taxcode, taxvalue from taxTrans
        group by taxTrans.TaxCode, taxtrans.taxvalue
        where taxTrans.SourceRecId == custinvoicetrans.recid
    && taxtrans.sourcetableid == custinvoicetrans.tableid
{
    FreeTextInvoiceLocalizationTmp.caption = taxtrans.taxcode;
    FreeTextInvoiceLocalizationTmp.cashdisc = taxtrans.taxvalue;
    FreeTextInvoiceLocalizationTmp.cashdiscamount = taxtrans.taxbaseamount * -1;
    FreeTextInvoiceLocalizationTmp.discamount = taxtrans.taxamount * -1;
    
        freeTextInvoiceLocalizationTmp.insert();
        freeTextInvoiceLocalizationTmp.clear();     
}   
}
}