SQL query help?

SELECT Count(*) FROM Work WHERE (UserID='user1' AND MAX(Finished)=0)

Work:-
+---+-------+--------+---------+----------+
| ID | JobID | UserID | Finished | Comment |
+---+-------+--------+---------+----------+
| 1 | 1 | user1 | 0 | ... |
| 2 | 1 | user1 | 1 | ... |
| 3 | 2 | user2 | 0 | ... |
| 4 | 3 | user1 | 0 | ... |
| 5 | 2 | user2 | 0 | ... |
| 6 | 2 | user1 | 1 | ... |
| 7 | 3 | user1 | 0 | ... |
+---+-------+--------+---------+----------+

All I want it to do is return the number of unfinished jobs for a specific
user.

In this example it would return 1 because job number 3 is not finished and
user1 was the last person working on it.

but I keep getting MySQL error #1111 - Invalid use of group function