Unable To Send Grouped Value To Subquery

resolving this problem the query is

SELECT DAY_NBR ||' '||HOUR_NBR ||' '||MINUTE_NBR AS "@TIMEPOINT",
RTRIM ( xmlagg (xmlelement (c, procedure_nm || ', ')).extract ('//text()'), ', ' ) AS "@LABEL",
RTRIM ( xmlagg (xmlelement (c, procedure_id || ', ')).extract ('//text()'), ', ' ) AS "@PROCEDURE_ID",
cursor
(SELECT SUBJECT_NBR AS "@LABEL",TO_CHAR (PSUB.procedure_tm,'HH24:MI') AS "@TIME",
PROCEDURE_ID AS "@PROCEDURE_ID", PROCEDURE_SUB_ID AS "@PROCEDURE_SUB_ID"
FROM PROCEDURE_SUBJECT_TIME PSUB WHERE PSUB.ACTIVE_FLG = 1
AND PSUB.PROCEDURE_ID in pr.PROCEDURE_ID
ORDER BY PSUB.procedure_tm,PROCEDURE_ID
)AS VOLUNTEER
FROM SCHEDULE_PROCEDURE PR
WHERE active_flg = 1 and SCHEDULE_ID = 200900195269 group BY day_nbr,hour_nbr,minute_nbr,procedure_nm;

and the error getting is ORA-00979: not a GROUP BY expression