private bool fnValidateExpression(ref string strString, ref bool bIsNotCaseExpression)
        {
            try
            {
                strString = txtExpression.Text.Replace("Field.", "").Trim().ToUpper();

                if (strString.StartsWith("="))
                {
                    strString = strString.Substring(1);
                }
                if (strString == "")
                {
                    strString = "1=1";
                }

                clsDataSource clsObj = new clsDataSource();

                DataTable dtSource = clsObj.fnValidateExpressEditor(strString, strTabName, iExpressionFor);

                if (dtSource != null)
                {
                    LabelParserResult.Text = "Success!";
                    LabelParserError.Text  = "";
                    if (strString == "1=1")
                    {
                        strString          = "";
                        txtExpression.Text = "=";
                    }
                    return(true);
                }

                return(false);
            }
            catch (Exception ex)
            {
                LabelParserResult.Text = "Constant: Failed!";
                LabelParserError.Text  = "Exception: " + ex.Message;
                throw ex;
            }
        }