Percentile_Cont function throwing error

I have this query where I am trying to introduce a non-static value into PERCENTILE_CONT:

SELECT perf2.REVIEW_PERIOD
     , PERCENTILE_CONT(goalsASP.GOAL*.01) WITHIN GROUP (ORDER BY AVG_AMT ASC) ast75 
FROM repDB.TBL_PERFORMANCE perf2 JOIN
      pz.CATEGORY C on perf2.DEPTCAT = C.id JOIN
      repDB.TBL_GOALS_MATRIX goalsASP ON C.NAME = goalsASP.DIMENSION_Y
                                       and perf2.REVIEW_PERIOD = goalsASP.SNAP_NAME 
                                       and goalsASP.DIMENSION_X = 'asp'
GROUP BY perf2.REVIEW_PERIOD

The error thrown is:

ORA-30497: Argument should be a constant or a function of expressions in GROUP BY. 30497. 00000 - "Argument should be a constant or a function of expressions in GROUP BY."

This is in a view, it was working fine when goalsASP.GOAL*.01 was .75 and I have a stored procedure where feeding a column as an argument works just fine so I'm kind of at a loss for what I'm doing wrong here.