Unable to reset page number on repeating frame

 I have a custom built report . The issue is with the page numbers on the repeating frame. This report generates mutilple invoices. Few of the invoices are single page and few of them go on to more than one page. When its a single page invoice , the report should not display the page number. But for example, if its a 3 page invoice , the page number should be page 1 of 3, page 2 of 3, page 3 of 3 . So I have a format trigger that takes care of the single page invoices. Regarding the