Hours Between

Hours Between

Hi, I am trying to get hours_between on this query but its coming up as an unsupported function? 

SELECT
dl."Lead Source" AS "Lead Source",
dl."Lead Created Time" AS "Lead Created Time",
days_between(dl."Lead Created Time", dl."First Activity Occurred") AS "Days to Contact",
COUNT(1) AS "Deal Count"
FROM  "Deals (Zoho CRM)" AS  dl 
GROUP BY dl."Lead Source",
dl."Lead Created Time",
  days_between(dl."Lead Created Time", dl."First Activity Occurred") 


Can anyone help?