COUNT and GROUP BY performing strangely

Hi everyone,

Any thoughts on the below three queries please?

james_traffic=# SELECT count(*) FROM stage;
count
--------
430991
(1 row)

james_traffic=# SELECT bad_flag, count(bad_flag) FROM stage GROUP BY bad_flag;
bad_flag | count
----------+-------
| 0
1 | 4102
(2 rows)

james_traffic=# SELECT count(bad_flag) FROM stage;
count
-------
4102
(1 row)

I'm confused as to why the second query doesn't return this:

bad_flag | count
--------------+-------
| 426889
1 | 4102

It should count the records surely, even if the field is blank/null ?

Thanks

James