slidingExpiration is not working when sessionstate timeout

Question

Hi,

in my asp.net web site set slidingExpiration="true" to redirect to same page when login again after logout when timeout expired.but this is not working when sessionstate timeout expired.ie sessionstate timeout is 2 and authentication time out is 4 then when I try to login after 5 min of inactivity it is not redirecting to the same page.if I set sessionstate timeout a greater value than authentication timeout then it works.