query problem after moving from mysql 3.0 to 5.0

i am having problems with this query which worked perfrcly on mysql
3.0.
It is able to extract dowloaders from a table and group them by date.


select count(*) AS downloaders, date_format(date,'%Y-%m-%d') AS
Datesmall, date_format(date,'%D %M %Y') AS Date from downloaders Group
By date_format(date,'%D %M %Y ') order by unix_timestamp(date)")


After moving to 5.0 the query does not work.
I dont have a qyery error but just the query retrieve always zero
items.
After i series of tests i noticed that what is not working is

where unix_timestamp(date) between unix_timestamp('" & From_YY & "-" &
From_MM & "-" & From_DD & "') and unix_timestamp('" & To_YY & "-" &
To_MM & "-" & To_DD & "23:59:59')

which i use to get only downloaders from a range of date.
But i dont know what changed from 3.0 to 5.0 in order to make the query
stop working.
any advice?