need help in writing sql server query : My data is look like below (usually more than 2 records)

OBLIGOR  OBN_NUM     XPTYPE NET_UNUSED BANK_ASSET
 1       000100000   0101    100         0
 1       000100001   5151    100         0
 1       000100002   5151     50         0

when i use the below sql, i am able to sum as 100 only ( but i want to get 250).

    SELECT  SUM(NET_UNUSED)+SUM(BANK_ASSET) AS BANK_ASSET,  OBLIGOR AS OBLIGOR, 
     SUBSTRING (OBN_NUM,1,4) AS OBN_NUM FROM RB_CRM_DEV.[IN].STG_SF_I_DC
          WHERE SUBSTRING (OBN_NUM,1,4) = SUBSTRING (OBN_NUM,1,4)
            AND SUBSTRING( XPTYPE,1,1) IN (0,1)
         GROUP BY  OBLIGOR, SUBSTRING (OBN_NUM,1,4)
         ORDER by OBLIGOR,SUBSTRING(OBN_NUM,1,4)

how do i make sure my set of record should have xptype as 0,1 for atleast record to check in this query ( since SUBSTRING( XPTYPE,1,1) IN (0,1) condition drops the other two records)
