residual payment

hi,

in residual payment method, system is creating one more document for part payment. ( for ex. Rs.5000 is bill amount and we paid Rs.3000 so systems clear the bill for Rs.5000 and it is showing Rs.2000 is to be paid)

when i go to for further payment through F-58 the reference document i.e actual bill document is not showing in reference field. but in FBL1N, system is showing the Invoice reference.

how do i get the reference number while making payment.

govind.