Session variable in IFrame

i am calling an asp-website in iframe of my html page.
after login from sign-in page of iframe's website, i can't get the session variables of iframe's website in redirect page into the iframe

i can't get the session variables of iframe's website in redirect page into the iframe

How you are doing this?

my html page has only one iframe (not any other control).
iframe has form of another website, which require to login for any user to see its webpages.
when i sign-in from this website, login form made the session variables but i can't get these session variables in another page of website in iframe.

this problem is only in IE, Mozilla works properly.

where are you opening the 2nd page?
On the same window or another window?

into the same iframe

Are those pages are continous?

Explain the full scenario...