Functionality issue?

I have a form page and when it’s complete it returns to the referring page.

in the form page:
session_start();
$_SESSION[‘mykey’] = “myvalue”;

referring page
echo $_SESSION[‘mykey’];

it echo’s nothing. I have tried multiple tests and it seems to not store session data between pages. Any suggestions? If I store the session var and echo it in the same page it works, so I am at a loss.

Thanks!