Counting People With Same Birthdays

I have a q, If i have:

table1(p_id, birth_date,lid)
table2(lid)
table3(s_id, birth_date, lid)

Now i would like to count from table 1 all p_id with birthday is the same as a s_id.Currently i am doing this:

select s_id, count(tbl1.pid)
inner join table 3
using (lid)
inner join table 1
using (lid)
Where to_char(tbl1.birth_date,'DD') = to_char(tbl2.birth_date,'DD') AND
to_char(tbl1.birth_date,'MM') = to_char(tbl2.birth_date,'MM')

when i check it using data, i get a target_id whose birth_day is same as TWO people in tbl1 yet according to that query i am only getting ONE person! rest of the results from that query look fine!