how to SUM two different columns in two different table between two date

this may quere:

select sum(tableA.value)+sum(tableB.value1) ) from tableA,tableB where tableA.data between '2016-01-21' and '2016-03-09' and tableB.date2 between '2016-01-21' and '2016-03-09'

but result false where number row different , that's to say whenever tableA select 2 row and tableB select 3 result is false.. if table ay value = 2 and tableB value =3,5 result =12 this false.. result =10