EF CF 4.2 and SQL Instead of insert trigger

I have a CF class:

public class A
 {
   [Key, DatabaseGenerated(DatabaseGeneratedOption.Identity)]
   public int Id {get;set;}
   [Required]
   public string Name {get;set;}
   public string LoweredName {get;set;}
   [Timestamp]
   public byte[] RowVersion {get;set;}
 }
 

In the database i have a trigger:

CREATE TRIGGER IOI_LoweredName
    ON  Abc
    INSTEAD OF INSERT
 AS; 
 BEGIN;
     SET NOCOUNT ON;
 
     INSERT INTO Abc(Name, LoweredName) SELECT Name, LOWER(Name) FROM inserted
 END;
 

Now if i try to insert a record:

dc.Names.Add(new A { Name = "Test" });
 dc.SaveChanges();
 

I get the following error:

Store update, insert, or delete statement affected an unexpected number of rows (0). Entities may have been modified or deleted since entities were loaded. Refresh ObjectStateManager entries.
 

Any ideas how to get around this?
All my classes inherit from a base class that has the RowVersion (Timestamp) column. Can't i use such a simple trigger with EF when using concurrency on a timestamp field ?

Updated

There is a primary key (also added it to the example above).

Update 2

This is from the SQL Profiler:

declare @0 nvarchar(100)
 set @0=N'Test'
 insert [dbo].[abc]([Name], [LoweredCompanyName]) values (@0, null)
 select [Id], [RowVersion] from [dbo].[Abc] where @@ROWCOUNT > 0 and [Id] = scope_identity()
 

Problem is that the select doesn't return anything.

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