Entity Framework issue at associating a subclass with another class not in the hierarchy

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entity-framework

Under the following model: [url=http://www.freeimagehosting.net/][img]http://www.freeimagehosting.net/uploads/258829be4d.jpg[/img][/url]

BaseClass
id <PK>
testProperty
SubClass: BaseClass
idSubClass <PK removed after inheriting from baseclass>
Nav Property
SubClassRelated

SubClassRelated
idSubCLassRelated <PK>
Athing
Nav Property
SubClass

I receive the following error when validating:
"Error 3024: Problem in Mapping Fragment starting at line 129: Must specify mapping for all key properties (id) of End SubClass in Relationship FK_SubClassRelated_SubClass."
The association cannot be done because I have lost the PK in SubClass after creating the inheritance relation with BaseClass... is that possible to have associations in subclasses when the PK is on the subclass?
Including the schema here just in case it helps:
CREATE TABLE [dbo].[BaseClass](
[id] [int] IDENTITY(0,1) NOT NULL,
[testProperty] [nvarchar](20) NOT NULL,
CONSTRAINT [PK_BaseClass] PRIMARY KEY CLUSTERED
(
[id] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
CREATE TABLE [dbo].[SubClass](
[idSubClass] [int] IDENTITY(0,1) NOT NULL,
[id] [int] NOT NULL,
CONSTRAINT [PK_SubClass] PRIMARY KEY CLUSTERED
(
[idSubClass] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]
CREATE TABLE [dbo].[SubClassRelated](
[idSubClassRelated] [int] IDENTITY(0,1) NOT NULL,
[AThing] [nvarchar](20) NOT NULL,
[idSubClass] [int] NULL,
CONSTRAINT [PK_SubClassRelated] PRIMARY KEY CLUSTERED
(
[idSubClassRelated] ASC
)WITH (IGNORE_DUP_KEY = OFF) ON [PRIMARY]
) ON [PRIMARY]