not able to union subqueries

[inkrement]

> union_all(genres1, genres2, genres3) %>% group_by(channel_id, genre) %>% 
+   summarize(c = sum(num)) %>% ungroup() %>% as.data.frame()
Error in clckhs::select(conn@ptr, statement) : 
  DB::Exception: Syntax error: failed at position 55 (line 2, col 7): (SELECT `channel_id` AS `channel_id`, `genre` AS `genre`, `num` AS `num`
FROM (SELECT `channel_id`, `genre`, COUNT() AS `num`
FROM (SELECT *
FROM `videos1`) `uv, expected SELECT