Linq to Sql Delete (Disconnected Object)

[daokfella]

I want to delete on object from my datacontext. I know that the
following works:

MyObjectType myobject = MyDataContext.M yObjects.Single (o =>
o.MyObjectId == id);
MyDataContext.M yObjects.Delete OnSubmit(o);
MyDataContext.S ubmitChanges();

However, this hits the database twice (once for fetch, once for
delete). I thought I was able to delete an object with a single hit by
attaching an entity simply setting the primary key like this:

MyObjectType myobject = new MyObjectType ();
myobject.MyObje ctId = id;
MyDataContext.M yObjects.Attach (c);
MyDataContext.M yObjects.Delete OnSubmit(c);
MyDataContext.S ubmitChanges();

However, this doesn't work. I profiled SQL and the statements run are
this:
DELETE FROM [dbo].[MyObjects] WHERE 0 = 1 <--- STRANGE!
SELECT NULL AS [EMPTY]
FROM [dbo].[INcite_MyObject s] AS [t0]
WHERE [t0].[MyObjectId] = @p0',N'@p0 int',@p0=16

Am I missing something or just completely misunderstandin g how it's
supposed to work? I understand perhaps why it wants the complete
record (for concurrency), but it seems silly to fetch just to delete.

Thanks,

Jason