Subtraction problem?

I must be doing something wrong here, but I can't for the life of me
figure it out.

SELECT gifts.*,
count(distinct bookmarks.id) as bmcount,
(select sum(have_it) from bookmarks as b1 where b1.gift_id=gifts.id)
as c_count_haveit,
( (count(distinct bookmarks.id)) - (select sum(have_it) from
bookmarks as b2 where b2.gift_id=gifts.id)) as c_count_wantit
FROM bookmarks, gifts
WHERE bookmarks.gift_id = gifts.id group by gifts.id

This returns:
bmcount of 1
c_count_haveit of 1
c_count_wantit of 1

But that should be impossible, as far as I can tell. The line that
determines the value of c_count_wantit is just subtracting bmcount
from c_count_haveit. So, shouldn't it be zero? If I replace either
of the sides of the equation with 1, I get the zero I expected. So,
both seem to be returning one, but when I put them together and
subtract one from one - I get one!

Anyone see what I'm doing wrong?

Many thanks,
Tom Lianza