MySql.Data.MySqlClient.MySqlException: Parameter '?@IDENTITY' must be defined
  at MySql.Data.MySqlClient.MySqlCommand.SerializeParameter (MySql.Data.MySqlClient.PacketWriter writer, System.String parmName) [0x00000] 
  at MySql.Data.MySqlClient.MySqlCommand.PrepareSqlBuffers (System.String sql) [0x00000] 
  at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader (CommandBehavior behavior) [0x00000] 
  at MySql.Data.MySqlClient.MySqlCommand.ExecuteReader () [0x00000] 
  at MySql.Data.MySqlClient.MySqlCommand.ExecuteScalar () [0x00000] 
  at (wrapper remoting-invoke-with-check) MySql.Data.MySqlClient.MySqlCommand:ExecuteScalar ()
  at PetShop.Components.Database.ExecuteScalar (System.String connString, CommandType cmdType, System.String cmdText, MySql.Data.MySqlClient.MySqlParameter[] cmdParms) [0x00000] 
  at PetShop.Components.OrderCOM.Insert (PetShop.Components.Order order) [0x00000] 
  at <0x00000> <unknown method>
  at (wrapper managed-to-native) System.Object:__icall_wrapper_mono_remoting_wrapper (intptr,intptr)
  at (wrapper remoting-invoke) PetShop.Components.OrderCOM:Insert (PetShop.Components.Order)
  at (wrapper remoting-invoke-with-check) PetShop.Components.OrderCOM:Insert (PetShop.Components.Order)
  at PetShop.Web.OrderProcess.OnLoad (System.EventArgs e) [0x00000] 
  at System.Web.UI.Control.LoadRecursive () [0x00000] 
  at System.Web.UI.Page.InternalProcessRequest () [0x00000] 
  at System.Web.UI.Page.ProcessRequest (System.Web.HttpContext context) [0x00000] 



with @@IDENTITY:

System.NullReferenceException: Object reference not set to an instance of an object

with @IDENTITY:

same thing as @@IDENTITY