Pagination showing negative number while exporting to PDF

HI,

I am using SQL 2005 and I am resetting the page to 1 for each new group (CUSTOMER_CODE) with page break at end. 

I am using the below VB code to reset the page:

Shared offset As Integer

Public Function GetPN(reset As Boolean, pagenumber As Integer) As Integer
  If reset
    offset = pagenumber - 1
  End If
  Return pagenumber - offset
End Function

ANd then referring this function in page header to reset the page no. to 1 for each new customer on new page. 

Everything works fine with pagination and resetting also correctly both in local visual studio as well as in web browser. But the problem comes when export to PDF in which it is not displaying correct values and showing some random negative number for the page.

Can you advise do I need to change the above VB code or to set some other property so that it can work for PDF as well.

Thanks