Can't execute query

SELECT p.id FROM store_tw p, profession_tw c, store_category_tw as it WHERE p.id = it.pid AND c.id = it.category AND p.available = '1' AND c.available = '1' AND p.postDate <= '2018-06-26' AND p.expireDate >= '2018-06-26'  AND it.category in () GROUP by it.pid

MySQL Error: You have an error in your SQL syntax; check the manual that corresponds to your MySQL server version for the right syntax to use near ') GROUP by it.pid' at line 1

This script cannot continue, terminating.