Type 2 SCD -- does not update the old value.

Question

I have following columns in the source table:
SSN, credit_score
In the target, I have following columns,
SK_ID, SSN, credit_score, flag
I am flagging the old credit_score as 'N' when updating the row and at the same time it is supposed to enter a new credit score with flag 'Y' in another row.
Second, If a row is completely new, It should be inserted with the flag 'Y'.
SK_ID is the surrogate key and SSN is the natural key, My trigger column is credit_score.
The problem is that when I run this type 2 mapping, it does not update anything but inserts the new rows only.
I have posted the screen shots at the following link.
http://www.box.net/shared/ea9v48r0xa
Thanks for your help in advance.

Answer 1

First of all, thanks for the reply...
You can also look at the screen shots I posted in previous post.
Here is how I am updating the rows (update logic).
If source_SSN=target_SSN and source_credit_score!=target_credit_score
then flag = 'N' (this is the update from 'Y' to 'N' after which i will insert a new row containing new value of credit_score with flag 'Y')
As an example, if my old rows in the target table were:
sk_id SSN credit_score flag
101 2212 654 Y
102 3023 707 Y
Now let's say my source table has these values.
SSN credit_score
2212 648
2220 690
Then my target table should be like this:
sk_id SSN credit_score flag
101 2212 654 N
103 2212 648 Y
102 3023 707 Y
104 2220 690 Y
Do you see what I mean...