Get Primary Key of newly inserted record in SQL Server 2008/VB.net

I have code which

- inserts a record into table 1 (this works)
- attempts to grab the primary key value of that record (this does not work)
- inserts a related record into table 2.  I am trying to include the primary key from the earlier insert, but the @@IDENTITY returned is null

The field type of the primary key is "uniqueidentifier"

What am I doing wrong?  Or is there a better way to do this?


 

           Dim cn As New SqlConnection
            Dim cmd As New SqlCommand

            cn = GetConnected()
            cmd.Connection = cn

            cmd.CommandText = sSQL
            cmd.Parameters.Add(New SqlParameter("@FromDate", SqlDbType.DateTime))
             ' etc - more parameters added

            '  This works - the record is added with a visible uniqueidentifier
            cmd.ExecuteNonQuery()

            ' This is where I'm trying to grab the Primary Key, but it returns a null....
            cmd.Parameters.Clear()
            cmd.CommandText = "SELECT @@IDENTITY"
            Dim newID As String = "" & cmd.ExecuteScalar()

            ' ... so all of the record added here have a blank SessionID
            sSQL = "INSERT INTO tblScheduleStuff (Scheduler_SessionID, GenericStuff) SELECT '" & newID & "', Stuff FROM tblTEMPStuff"
            cmd.CommandText = sSQL
            cmd.ExecuteNonQuery()

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