The identity column must be of data type int, bigint, smallint, tinyint, decimal, or numeric

The identity column must be of data type int, bigint, smallint, tinyint,
decimal, or numeric

I have created a database project in Visual Studio 2012, with target
platform set to 'Windows Azure SQL Database'. I added a table like:
CREATE TABLE [dbo].[Organization]
(
[Id] UNIQUEIDENTIFIER NOT NULL PRIMARY KEY NONCLUSTERED IDENTITY,
[Name] NVARCHAR(100) NOT NULL,
[CreationDate] DATETIME NOT NULL DEFAULT GetDate()
)
GO
CREATE CLUSTERED INDEX [IX_Organization_CreationDate] ON
[dbo].[Organization] ([CreationDate])
But it keeps complaining about:
Error 1 SQL71518: The identity column '[dbo].[Organization].[Id]' must
be of data type int, bigint, smallint, tinyint, decimal, or numeric with a
scale of 0, and the column must not be nullable.
C:\Projects\Gastrology\MGP\trunk\Sources\Cfg.Mgp.Infrastructure.Database\Organization.sql
3 2 Cfg.Mgp.Infrastructure.Database
Anyone knows why I can't create a primary key of type guid? What Am I
doing wrong?
Thanks!