I solve my problem formatting the string from the datasource.
Ex.
var oSImporteA = oform.DataSources.UserDataSources.Item("SYS_94"); var oSDocTotal = oform.DataSources.UserDataSources.Item("SYS_91"); _oRc.DoQuery("SELECT top 1 currency from ACRD where currency like '%RD$%'"); //query to get the currency var importeSap = Convert.ToDouble(oSImporteA.ValueEx == "" ? "0" : oSImporteA.ValueEx.Replace(_oRc.Fields.Item(0).Value + " ", " ")); var importeAp = (importeSap + _importeEfectivo + TotalAPagar); var totalDoc = Convert.ToDouble(oSDocTotal.ValueEx == "" ? "0" : oSDocTotal.ValueEx.Replace(_oRc.Fields.Item(0).Value.ToString(), " ")); editaText.String = _oRc.Fields.Item(0).Value + " " + importeAp.ToString("N", new CultureInfo("en-US")); editSaldo.String = _oRc.Fields.Item(0).Value + " " + (totalDoc - importeAp).ToString("N", new CultureInfo("en-US"));