Rebuilt it from scratch. I indeed do not need the ID in the model and in InsertParameters. And it works, almost....
When I hit Save, I receive the following message:
Status Code: 200Status Text: BADRESPONSE: Syntax error
{serviceResponse:{success:false,message:"System.Ex ception: Sequence contains no matching element ---> System.InvalidOperationException: Sequence contains no matching element\r\n at System.Linq.Enumerable.Single[TSource](IEnumerable`1 source, Func`2 predicate)\r\n at Ext.Net.Store.InsertCallback(Int32 recordsAffected, Exception exception) in C:\\Users\\Geoffrey McGill\\Documents\\Visual Studio 2010\\Projects\\Ext.NET\\v2\\Ext.Net\\Ext\\Data\\S tore.cs:line 1053\r\n at System.Web.UI.DataSourceView.Insert(IDictionary values, ....
I am not sure how to address it.
Despite the message, the record is added / updated.