SQL & PL/SQL

Hi Guys,

I am trying to get a count of the number of failed SR's in the following query. The table I need to get the information from I cannot put into the main body of the query as it would bring some results back that I do not want. The query I have is as follows:

SELECT DISTINCT env_subtype_code,
  std_count,
  cust_count,
  esc_sr,
  fail_sr,
  SUM(std_count+cust_count) total,
  (esc_sr      *100)/DECODE(SUM(std_count+cust_count),0,1,SUM(std_count+cust_count)) esc_per,
  (fail_sr     *100)/DECODE(SUM(std_count+cust_count),0,1,SUM(std_count+cust_count)) sentback_per
FROM
  ( SELECT DISTINCT env_subtype_code,
    COUNT(
    CASE
      WHEN sr_type IN ('100', '231')
      THEN 1
    END) std_count,
    COUNT(
    CASE
      WHEN sr_type = '101'
      THEN 1
    END ) cust_count,
    COUNT(
    CASE
      WHEN escalated          = 'Y'
      AND upper(patch_status) = 'CLOSED'
      AND group_name          = 'AITSYS ESCALATIONS'
      THEN 1
    END ) esc_sr,
    COUNT(
        SELECT sent_back_date
        FROM cprt_sent_back_srs
        WHERE b.creation_date BETWEEN to_date('01-DEC-08', 'DD-MON-RR' ) AND to_date('31-DEC-08', 'DD-MON-RR')
        ) fail_sr
  FROM cprt_request a,
    cprt_patch_update b,
    cprt_patch_sr c,
    environment_subtype sub,
    environment env,
    GSA.GSA_SR_JTF_RS_GROUPS_VL gs
  WHERE a.cprt_request_id = b.cprt_Request_id
  AND b.cprt_patch_sr_id  = c.cprt_patch_sr_id
  AND b.patch_group       = gs.group_id
  AND a.sid               = env.name
  AND sub.id              = env.env_subtype_id
  AND to_date(b.sr_closed_date,'DD-MON-RR') BETWEEN to_date('01-DEC-08', 'DD-MON-RR' ) AND to_date('31-DEC-08', 'DD-MON-RR' )
  AND env.type             IN( 'Production','Test')
  AND env.status           <> 'Decommissioned'
  AND (sub.env_subtype_code = '-1'
  OR :P208_ENV              = '-1')
  GROUP BY env_subtype_code
  ORDER BY env_subtype_code
  )
GROUP BY env_subtype_code,
  std_count,
  cust_count,
  esc_sr,
  fail_sr
ORDER BY env_subtype_code

The part of the code I need to work but am getting errors with is:

COUNT(
        SELECT sent_back_date
        FROM cprt_sent_back_srs
        WHERE b.creation_date BETWEEN to_date('01-DEC-08', 'DD-MON-RR' ) AND to_date('31-DEC-08', 'DD-MON-RR')
) fail_sr

The error I get is ORA-00936 - Missing Expression. I know this is probably because you cannot put a subquery into a count like I have. Is there anyway I can use the query in the count to show as a column in my query without putting the clause into the main body of my query?

Thanks
-Mark