Project 3: case study 2 task B

my query is getting executed but its not giving any output? please check any one and let me know where I'm doing mistake. select yearnum, weeknum, activeusers, sum(activeusers) over (order by yearnum, weeknum rows between unbounded preceding and current row) as cum_users from( select extract(year from activatedat) as yearnum, extract(week from activatedat) as weeknum, count(distinct userid) as activeusers from users where state = 'active' group by yearnum, weeknum order by yearnum, weeknum)a