Problem Returning A Timestamp Column Inside An TSQL Transaction

I cannot manage to fetch the new timestamp value inside a TSQL Transaction.  I have tried to Select "@LastChanged" before committing the transaction and after committing the transaction. A TimestampCheck variable is used to get the timestamp value of the Custom Business Object. It is checked against the row updating to see if they match.  If they do, the Update begins as a Transaction.  I send @LastChanged (timestamp) and an InputOutput param, But I also have the same problem sending in a dedicated timestamp param ("@NewLastChanged"):
  1 select @TimestampCheck = LastChanged from ADD_Address where AddressId=@AddressId
2
3 if @TimestampCheck is null
4 begin
5 RAISERROR ('AddressId does not exist in ADD_Address: E002', 16, 1) -- AddressId does not exist.
6 return -1
7 end
8 else if @TimestampCheck <> @LastChanged
9 begin
10 RAISERROR ('Timestamps do not match up, the record has been changed: E003', 16, 1)
11 return -1
12 end
13
14
15 Begin Tran Address
16
17 Update ADD_Address
18 set StreetNumber= @StreetNumber, AddressLine1=@AddressLine1, StreetTypeId=@StreetTypeId, AddressLine2=@AddressLine2, AddressLine3=@AddressLine3, CityId=@CityId, StateProvidenceId=@StateProvidenceId, ZipCode=@ZipCode, CreateId=@CreateId, CreateDate=@CreateDate
19 where AddressId= @AddressId
20
21 select @error_code = @@ERROR, @AddressId= scope_identity()
22
23 if @error_code = 0
24 begin
25 commit tran Address
26
27 select @LastChanged = LastChanged
28 from ADD_Address
29 where AddressId = @AddressId
30
31 if @LastChanged is null
32 begin
33 RAISERROR ('LastChanged has returned null in ADD_Address: E004', 16, 1)
34 return -1
35 end
36 if @LastChanged = @TimestampCheck
37 begin
38 RAISERROR ('LastChanged original value has not changed in ADD_Address: E005', 16, 1)
39 return -1
40 end
41 return 0I do not have this problem if I do not use a TSQL Transaction. Is there a way to capture the new timestamp inside a Transaction, or have I missed something?Thank you,jspurlin