There is no form past being made to the detail page, so the code on the detail page for setting the session value will never be triggered.
On the insert page, the code for setting the session variable needs to be after the Upload File code , but before the Inssert Record code.
move the code at lines 98 - 102:
if (cStr(WA_DFP_UploadObj.Form("Insert.x")) <> "") then
Session("AddressID") = "" & cStr(WA_DFP_UploadObj.Form("cAddressID")) & ""
to line 44 so that the session is created after the file is uploaded and before the record is inserted.