Problem in retrieving values from session in other pages.

Hi all ,
I am creating an application in which in one page(Default.aspx) I am assigning some values into session varaible like-
session["NameOfSession"]="some values#SomeValues";

When I am going to retrieving this value on next page(let ViewResult.aspx) like
if(Session["NameOfSession"] ==null)
{
lbl.Text="Session having null values";
}
else
{
lbl.Text="Session having some values";
}

Then in each case "Session having null values" going to print in Label.(I had check spelling of session name :- )  ). Same code running fine on local Mac.
And sometimes on some MAC code are running fine(Session's values are being retrieve as it had send from prevous page.)

Please help as I never face such a problem.
Thanks in advance

Kapil Dev