Calling dynamic stored procedure results

gistfile1.cs

        [WebInvoke(BodyStyle = WebMessageBodyStyle.Wrapped, Method = "POST", UriTemplate = "ExecuteReportData", RequestFormat = WebMessageFormat.Json, ResponseFormat = WebMessageFormat.Json)]
        public string ExecuteReportData(int parameter1, string reportName)
        {
            try
            {
                List<dynamic> returnList = new List<dynamic>();

                if (isApprovedUser())
                {
                    using (var db = new MyReportingEntities())
                    {
                        
                        var dbCommand = db.Database.Connection.CreateCommand();
                        dbCommand.Connection.Open();

                        dbCommand.CommandText = "GenerateReportData";
                        dbCommand.CommandType = System.Data.CommandType.StoredProcedure;
                        dbCommand.AddParameterWithValue("@ReportName", reportName);
                        
                        DbDataReader reader = dbCommand.ExecuteReader(System.Data.CommandBehavior.CloseConnection);

                        while (reader.Read())
                        {
                            returnList.Add(SqlDataReaderToExpando(reader));
                        }
                    }
                }
                return JsonConvert.SerializeObject(returnList);
            }
            catch (Exception ex)
            {
                logger.ErrorException(String.Format("ExecuteReportData({0}, {1})", parameter1.ToString(), reportName), ex);
                return null;
            }
        }