Look into the SectionPages field. (There is no SectionPage field. You need to restart numbering and use the Page field.)

Here is more background on the fields involved: Pagination Fields

See the solution to this where dual page x of y formatting was also needed in Greg Maxey's page on Page Numbering. This deals with the page number in the document as well as page number in the section. I.e.

Section Page 12 of 17
Document Page 43 of 312