Problme in accessing request.servervariables("http_referer") on Mac

[sut]

Hello,

I am using the Request.ServerVariables("HTTP_REFERER&quot as follows in "index.asp".

'if instr(request.servervariables("http_referer&quot, "index.html&quot =0 or request("userid&quot="" then
Response.redirect "index.html"
else
userid=request("userid&quot

It works fine on PC but doesn't work on Mac. I am getting correct values of "userid" so there must be something wrong with request,servervariables("http_referer" )

Does any body has any idea why it doesn't work on Mac?
Is there some other reason why
Request.ServerVariables("HTTP_REFERER&quot would return different information
from a Mac and IE5?

Waiting for reply.

Thanks
S