protected void btnAddCalc_Click(object sender, System.EventArgs e)
        {
            try
            {
                string measure1  = Request.Form[this.UniqueID + ":selCalcMeasure1"];
                string measure2  = Request.Form[this.UniqueID + ":selCalcMeasure2"];
                string operation = Request.Form[this.UniqueID + ":selCalcOperation"];

                _contr.AddCalculatedMeasure(measure1, measure2, operation);

                _report.SaveState();
            }
            catch (Exception exc)
            {
                ((PageBase)this.Page).ShowException(exc);
            }
        }