need help with user variables in where clause of sub query

[Dan Rossi]

Hi there i am trying to use usewr variables in a select statement to 
add to a where clause in a sub query. Ie

select @id:=id,@month:=month, (select SUM(totals) from table where 
id=@id and month=@month) as totals from table

its happened on other occasions ie with calculations and sums, whats 
happened in mysql5 ? It used to work in mysql4 , something i am doing 
is wrong ? Please let me know thanks.