System.Data.SqlTypes.SqlNullValueException: Data is Null. This method or property cannot be called on Null values.
   at System.Data.SqlClient.SqlBuffer.get_DateTime()
   at System.Data.SqlClient.SqlDataReader.GetDateTime(Int32 i)
   at Graphs_uc_highChartWithToolbox.SetExchangeStartEndTime(String exchange, String typeid) in c:\globes\wwwroot\Portal\Graphs\uc\highChartWithToolbox.ascx.cs:line 321