在wordpress模板中的另一个页面上获取自定义会话值

Question

I'm trying to make SESSION in WordPress and use my session value on another custom WordPress template. For Example:I'm trying to transfer value "$_SESSION['post_data']= $_POST['payvalue'];" from one page to another on Wordpress template but can't get it working. After submitting from First page to Second page Session array on the second page appears to be empty. On Second Page I print "<?php print_r($_SESSION); ?>" but it returns empty array.

I've already inserted session_start() at all page.

How can I use my custom session value on the second page in Wordpress template?