Document Map issue in SSRS 2008R2 rdl

I have a master report with a matrix. I have multiple sub reports inside the matrix. What I need to do is group by Vendor name and FeeId then have a document map for the vendors.

Problem: The document map doesn't work properly. When I preview the report or export the report to pdf, the document map doesn't point to the right page. 

When I add a page break to the group, the document map works fine except that I get empty page after each vendor.

PS: The report was working fine in SSRS 2005 which recently got migrated to SSRS 2008R2 with which the problem started. 

Thanks in advance.