How to set text of Text element in StimulSoft via code?

I try to set text of Text element in my stimulsoft report via code.I use this code in TextEditor windows into Expression tab.but don't work .I try to use this code into BeforPrintElement and AfterPrintElement events but in this case don't print any things. How to fix this?

    {if(ProcGetReportTRAINPDF.Fk_sellerCode=="8006")
      {
    AgencyCommission.value=  ((int.Parse(ProcGetReportTRAINPDF.Formula10)*2)/100).Tostring();
      }
if(ProcGetReportTRAINPDF.Fk_sellerCode=="8025")
      {
    AgencyCommission.value=  ((int.Parse(ProcGetReportTRAINPDF.Formula10)*1.8)/100).Tostring();
      }
    }