php - $_SESSION wont load first attempt

I got some script. And when I input username and pass it opens some fields to fill and to udapte mysql_query..

Here is the problem:

When I fill out the fields, it redirects me on process.php page. And process.php can't recognize the session username, but when I get back and fill it agian and press Submit, it works..

It happends every time (one time) when I open browser..

index.php

session_start();
$name= $_POST['name'];
$_SESSION['name']= $name;

process.php

session_start();
$name= $_SESSION['name'];