try this :
select_kpi =
SELECT
date,
SUM(kpi) AS kpi
FROM"sap.sample.db::CVKF_BUSINESSLOGIC" (
'PLACEHOLDER' = ( '$$IP_STARTDATE$$', to_Date(:lv_from_date)),
'PLACEHOLDER' = ( '$$IP_ENDDATE$$', to_date(:lv_to_date))
)
GROUPBYdate;
what is the error message ?