Assuming that for each CT.CASE_NUMBER and CASE_TIMES_TYPE your dataset has unique CASE_TIMES_DT_TM. then use the following
code first expression as =Only(CASE_TIMES_DT_TM)
second Expression= Above(total aggr(Only(CASE_TIMES_DT_TM),CT.CASE_NUMBER,CASE_TIMES_TYPE ) ,1)
if you have multiple timestamp for Case_Number & Case_TIMES_TYPE then use aggregation function in the first expression, something like max(CASE_TIMES_DT_TM)