ie6 postback asp.net

i have page contains user control only personalized dropdown list . i distribute any vigilant charge onclick=__dopostback('actrl',0).

when i click page postback glorious i got approaching results. however ie6 page doesn't change new values hallowed server.

the uncanny thing i change + click couple page reload glorious changes.

i attempted invalidate caching page nonetheless luck.

using code

response.cachecontrol = "no-cache"
response.addheader("pragma", "no-cache")
response.expires = -1
response.cache.setexpires(datetime.utcnow.addminutes(-1))
response.cache.setcacheability(httpcacheability.nocache)
page.response.cache.setexpires(datetime.now.adddays(-30))
page.response.cache.setcacheability(httpcacheability.nocache)
page.response.cache.setnoservercaching()
page.response.cache.setnostore()
response.cache.setnostore()

also i debug concentration i generated html rendered correct, nonetheless rendered.

this problem happens wholly ie6.