I suggest that you try inserting directly into the table, and check that the record appears in hana. This will check that your hana user has permission to insert and that the ODBC connection is correct
Here is an example of a simpler way to insert data into HANA using getdata :
CREATE SCHEMA Schema1 (SYMBOL string, VOLUME integer, PRICE float);
CREATE INPUT STREAM S1 SCHEMA Schema1;
CREATE FLEX Flex1
IN S1
OUT OUTPUT STREAM Flex1 SCHEMA Schema1
BEGIN
DECLARE
vector (typeof(S1)) v;
long n;
END;
ON S1 {
getdata(v, 'mel_hana_service', 'INSERT INTO DAVID.STOCK (SYMBOL, VOLUME, PRICE) VALUES (?, ?, ?)', S1.SYMBOL, S1.VOLUME, S1.PRICE);
};
END;