Late fee charge calculation on paid invoices

 Hi,

I am trying to charge late fees on paid invoices. If I want to calculate late fees on a monthly basis, how it can be done. This is a new set up, we are calculating late fees for the first time. For eg, I want to calculate late fees on July 1st, system should check for the invoices which were paid late during June month alone. I tried by creating a fee with start effective date as June 1st. But it didn't worked. Late fees are not calculated for the invoices which were paid late on June month.

Please help me out on this. Also please clarify about the Start effective date and end effective date on fee instructions.