Correct Usage of CARRYOVER Syntax in Advanced Formula Editor

Hello together,

we use the the action handler to take over an amount by using the carry over command.

In detail we would like to take over the value of the field marked with red to where the arrow is pointing.

The field marked with green is a field where values can be added manually. Right now there exists a formula to calculate the sum of the field marked with red.

Inside the action handler we have created a formula like shown in the following screenshot:

When executing the formula in the story we have the problem that the amounts are also taken from the total of the year 2020 which is not correct. It just has to be taken the sum of the last month and nothing else. In other words we need that just the value of 12.430 EUR is copied over.

How we can change the formular that this will work?

Thank you