sum of the last of 3 selected months

[#1]

hi

i got the following problem:

i want to sum only the last month even if 3 or more months are in a listbox  selected.

at the moment  the expression looks like this:

sum ( {  $ < TypeOfVoucher = { 'Sale' } , MonthNum = {  '9' '} >} Amount  )

I would be thankful for any advice.

greetings

daniel

[#2]

Try this:

sum ( {  $ < TypeOfVoucher = { 'Sale' } , MonthNum = {"=$(=Max(MonthNum))"}>} Amount  )

[#3 · Accepted solution]

Hello Marc,

thank for your good idea .

it led me to the right  solution.

the expression must  look like this:

sum ( { $ < TypeOfVoucher = {'Sale'}  , MonthNum = {    $ (=MAX (MonthNum ) )           }  > } Amount )

so long

daniel

Postscript: better type the whole expression without space characters.