Distributed transaction within a stored procedure

Hi, I have stored proc which goes something like this:

CREATE PROC sch_update_ccnd ( @ssn varchar(10), @bd datetime)
AS

DECLARE @trncnt int
SELECT @trncnt = @@trancount

IF @trncnt = 0
      BEGIN DISTRIBUTED TRAN succnd
ELSE
      SAVE TRAN succnd

IF EXISTS (SELECT ssn FROM int_lukebox.db.dbo.T WHERE ssn=@ssn)
BEGIN
      UPDATE int_lukebox.db.dbo.T
          SET bd=@bd
          WHERE ssn = @ssn
END
ELSE
BEGIN
      INSERT INTO int_lukebox.db.dbo.T(ssn,bd)
      VALUES(@ssn,@bd)
END

IF (@@ERROR != 0)
BEGIN
      ROLLBACK TRAN succnd
      RETURN -999
END

IF @trncnt = 0
      COMMIT TRAN succnd

RETURN 0
GO


This thing just hangs and never returns. Any pointers will be appreciated. If I remove all the transactional stuff from it, it executes fine. So something to do with distributed transactions and linked servers. BTW, the security context of the linked server has both read and write priviledges on both the servers.