Yes..after lot of work around i got solution. following code snippet works for me.
chartCoRel.Series.Add("TrendLine");
chartCoRel.Series["TrendLine"].ChartType = SeriesChartType.Line;
chartCoRel.Series["TrendLine"].BorderWidth = 3;
chartCoRel.Series["TrendLine"].Color = Color.Red;
string typeRegression = "Linear";
string forecasting = "1";
string error = "false";
string forecastingError = "false";
string parameters = typeRegression + ',' + forecasting + ',' + error + ',' + forecastingError;
chartCoRel.Series[0].Sort(PointSortOrder.Ascending, "X");
chartCoRel.DataManipulator.FinancialFormula(FinancialFormula.Forecasting, parameters, chartCoRel.Series[0], chartCoRel.Series["TrendLine"]);