#114 : Why my answer in incorrect?

I have done (daily_rev / prev_day_rev - 1) * 100.0.
My code is below:
WITH daily_rev AS
(SELECT order_dt, SUM(qty*unit_price_usd) AS daily_rev
FROM orders
GROUP BY order_dt
)
SELECT order_dt,
((daily_rev/ LAG(daily_rev, 1) OVER (ORDER BY order_dt)) - 1) * 100.0 AS dod_change
FROM daily_rev ;