Error while using Windows Function in SQL editor in SAP HANA

Hi Gurus,

I am trying to work with windows function in SAP HANA

I am using below query to partition data over a dimension

select class, val, offset,

  ROW_NUMBER() OVER  (partition by class order by val) as "row_num"

from T;

I am getting below error

Could not execute 'select class, val, offset, ROW_NUMBER() OVER (partition by class order by val) as "row_num" from ...' in 19 ms 136 µs . SAP DBTech JDBC: [257] (at 49): sql syntax error: incorrect syntax near "(": line 2 col 22 (at pos 49)

Table T is created using example for SQL reference manual

Please advice

Thanks,

Nikhil