Between Condition not working

I am attempting to calculate Age in months from the DoB - date of birth summited by a user.
if The computed age is between 35 - 45 then the condition is true.
I have tried using the BETWEEN condition but somehow it is not working.
When I test with the date 08-08-1977 it evaluates to true. What am I doing wrong

date451×742 46.9 KB

$_POST.a01_DoB.dateDiff('months', '2022-07-08'.between(420, 540))&&($_POST.a02_currentRank <= 8 && ($_POST.a02_DateAppointedPresent.dateDiff('months', '2022-07-08') >= 47.9))