How do I pass session variables from one ASP page to another ASP page?

After developing extensive procedures to save form variables to session variables in a membership renewal process, I have discovered that Response.Redirect results in the session variables being lost. Well, they are not entirely lost, but I can only save a certain number of them. Based on research, it sounds like none of them should persist through multiple pages, so I am concerned that the results could be random. I found an article (http://weblogs.asp.net/bleroy/Don_2700_t-redirect-after-setting-a-Session-variable-_2800_or-do-it-right_2900_) that says an overloaded version of Redirect should be used (Response.Redirect("~/default.aspx", false);). Tried that and get:
Microsoft VBScript compilation  error '800a0414'
Cannot use parentheses when calling a Sub
/membership/joinRenew/membershipSession2.asp, line 2266
Response.Redirect("membershipSelect_R2.asp", false)
---------------------------------------------------^

Have also tried Server.Transfer which appears to successfully accomplish the transfer, but I get a different error. The first thing that occurs in the activated page is the opening of a text log file:
<%
Dim conn, rs, sql, alreadyExists, lastName, iTotal
dim whichname, whichdir, whichFN
dim filesys, textfile
dim memText1, memQty1, memAmt1, midx, iidx, temp

whichdir=Server.Mappath ("\membership\joinRenew")
whichname="\coreturn.html"
whichFN=whichdir & whichname
set filesys = Server.CreateObject("Scripting.FileSystemObject")
set textfile = filesys.OpenTextFile(whichFN, 8, 0)%>

textfile.WriteLine "
===============================
" 
<%
Dim item1, quant1, amt1, item2, quant2, amt2, item3, quant3, amt3, item4, quant4, amt4, item5, quant5, amt5, item6, quant6, amt6, item7, quant7, amt7, item8, quant8, amt8, item9, quant9, amt9, item10, quant10, amt10, item11, quant11, amt11, item12, quant12, amt12, item13, quant13, amt13

item1                                = Session("sessitem_name1")
quant1                                = session("sessquantity1")
amt1                                 = session("sessamount1")
textfile.WriteLine Now
textfile.WriteLine "<BR><B>1:   </B>  " & (item1) & "     " & quant1 & "     " & amt1
textfile.WriteLine "<br>===============================<p>"...........................

Microsoft VBScript runtime  error '800a0046'
Permission denied
/membership/joinRenew/membershipSelect_R2.asp, line 13
(Line 13: set textfile = filesys.OpenTextFile(whichFN, 8, 0)%>)

This error doesn't occur when using Response.Redirect???
I've read everything I can find, and have yet to locate a solution. Is there one?