Customer Down Payment Process

Hi,

Please guide me in the customer down payment process.

I have made a 10000 as down payment to our customer in F-29.

After that i created Customer invoice using F-22.

After that i paid invoice amount thrugh f-39 with the clearing of down paymet.

Now my down payment was fullly utilized and inovice was also paid.

If i see in FBL5N the customer balance zero.

why should i again do the transaction in F-32.

Please guide me

Sateesh