i can't pass my variable to the next session in php code example

Example 1: create session in php

<?php 
  // Start the session
  session_start();

  // Set session variables
  $_SESSION["color"]= "blue";
  $_SESSION["animal"]= "dog";
  echo "The session variable are set up.";
?>

Example 2: send value from one page to another in php

//On page 1
$_SESSION['varname'] = $var_value;

//On page 2
$var_value = $_SESSION['varname'];