SQL & PL/SQL

SELECT
a.partc_ssn, a.partc_id, b.loc_id, e.loc_desc, c.cmpnt_beg_dte
, TO_CHAR(c.cmpnt_beg_dte,'YYYY')||CASE
WHEN SUBSTR(TO_CHAR(c.cmpnt_beg_dte,'YYYYMM'),5,2) IN ('01','02','03') THEN '1'
WHEN SUBSTR(TO_CHAR(c.cmpnt_beg_dte,'YYYYMM'),5,2) IN ('04','05','06') THEN '2'
WHEN SUBSTR(TO_CHAR(c.cmpnt_beg_dte,'YYYYMM'),5,2) IN ('07','08','09') THEN '3'
WHEN SUBSTR(TO_CHAR(c.cmpnt_beg_dte,'YYYYMM'),5,2) IN ('10','11','12') THEN '4'
END cmpnt_qtr

FROM etr_rgt_partc a,
etr_fst_partc_rgst b,
etr_fst_partc_cmpnt c,
etr_smt_fst_cmpnt_mstr d,
etr_smt_agy_loc_mstr e
WHERE a.partc_id = b.partc_id
AND b.partc_id = c.partc_id
AND b.fs_rgst_id = c.fs_rgst_id
AND c.cmpnt_nbr = d.cmpnt_nbr
AND b.loc_id = e.loc_id
AND B.LOC_ID LIKE 'SS00105'||'%'
AND a.partc_id = 2442344
AND (c.cmpnt_beg_dte BETWEEN '01-OCT-07'
AND '30-SEP-08')

GROUP BY a.partc_ssn,a.partc_id, b.loc_id, e.loc_desc, c.cmpnt_beg_dte,cmpnt_qtr;


i am getting Error cmpnt_qtr INVALID IDENTIFIED ...can anyone help me how to group by this ..