Measure in row shelf

Hello Experts,

following question:

I have a table Invoice and a table Bank.  In my Invoice Table are all my Invoices and in my Bank table i can see when my invoices were paid

Now for example i want to know in which months the Invoices of January were paid.

Invoice Sum of January 197$.

112$ were paid in January, 55$ in February, 30$ in March

Now i got this:

I try to get the Invoice SUM of a specific month (here 197$ of January) in the view.

I try to put the "money" field in the row shelf, make it discret or tried with an calculated field. nothing works .

Help would be appreciated.

Thanks

Walter