Multiple Number sequence in Sales Order form

Hi, 

I am wondering if some body could help me please . I have create a new number sequence on EDT and insert this EDT in my sales Table but it still not working on sales table coz i cannot over ride the create method correctly please help. my code is as follow 

void  create(boolean  _append = true)

{

    SalesTable   newSalesTable;

    DocuRef      RIP_docuRef;

    ;

   // element.numberSeqFormHandler().formMethodDataSourceCreatePre();

//super(_append);

   element.editSales(true);

    if (salesTableForm.create())

    {

      newSalesTable = SalesTable::find(salesTableForm.newSalesId());

//

       if (newSalesTable)

       {

element.numberSeqFormHandler().formMethodDataSourceCreatePre();       

super(_append);

element.numberSeqFormHandler().formMethodDataSourceCreate();

         salesTable.data(newSalesTable);

            RIP_docuRef = docuRef::find(curext(), newSalesTable.TableId, newSalesTable.RecId, newSalesTable.createdDate);

            if (RIP_docuRef && RIP_docuRef.RIP_SODocuRef)

            {

                element.RIP_displayDocuRef();

            }

            salesTable_ds.write();

            tabLineOverview.setFocus();

        }

    }

    else

    {

        this.editSales();

    }

}

Kind Regards,

Jahan