Session("uid") Problem

[mjm]

Am doing security for certain pages. Have everything in
place but whenever I try to use an If..then statement to
interrogate either the Session("uid") or any variable, I
get an error that the file cannot be found when the
Response.Redirect statement is executed. Executing the
Response.Redirect without If..then works just fine.
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Code is:

<%Response.Buffer = true %>
<%
Response.CacheControl = "no-cache"
Response.AddHeader "Pragma", "no-cache"
Response.Expires = -1
%>

<%Response.Clear%>

<%
uid = Session("uid")
If uid = ""
then
response.redirect "http://www.path/path.asp"
%>
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Also am trying to pass the Session("uid") variable and
that is not working either.
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The code is:

<%Session("uid")=cStr(fp_rs("ID"))%>
</p>
<a href= "MaintainDB.asp?uid=<%=Session("uid")%>"></a>
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Any help would be appreciated. Thank You