Session problems!

programming
1

Hello!
I have a problem which I cannot explain.
Now, I store in session an id, which is a number. The problem is that after loading a php page that number becomes 9…
I do not know why… but if the number is 2, it becomes 9, if it’s 1, nine also…
The page that loads is a php file, but actually no php code is executed - just loads the number from the session like this

session_name('agent');
session_start();
$agent=$_SESSION['id'];