Error Message: Scalar Type Not Allowed in SAP HANA

Few points about your code to create a Stored Procedure, that you can edit and try

PROCEDURE "SLT_DELETE"."HCDW.IT.IT::TO_TIMESTAMP_CALL" (IN IN_DATE DECIMAL(15),
   OUT OUT_DATE TIMESTAMP)
   LANGUAGE SQLSCRIPT AS
   --DEFAULT SCHEMA <default_schema_name>
   --READS SQL DATA AS
BEGIN
   select to_timestamp(IN_DATE) into OUT_DATE FROM DUMMY;
END;

In Line32, you have used below:

SELECT: ORGID_ARTIKEL into

However correct syntax should be like:

SELECT "ORGID_ARTIKEL" into