Why is COUNT (MIN(...)) in this case not working?

In this exercise: https://www.codecademy.com/paths/data-science/tracks/analyze-data-sql-analyze-real-data/modules/analyze-data-sql-marketing-attribution/projects/analyze-data-sql-attribution-queries

Why is this command not working and do I need a subquery to take into account min(timestamp):

SELECT user_id, count( MIN(timestamp)) AS first_touch_at
FROM page_visits
group by utm_campaign
LIMIT 5;

???
Thanks!!! :slight_smile: