Can't add perch tags to inner pages

I can't add perch tags to any page other than the index.php page : https://www.intakevets.co.uk/ If I add the same tags to another page I get a fatal error message: Fatal error: Call to undefined function perch_layout() in /home/intakeve/public_html/contact.php on line 2

I guess it is a problem with paths? I renamed the perch folder to admin, and everything else is working OK, I'm stumped!

Summary information

Perch: 2.8.13, PHP: 5.6.12, MySQL: 5.5.32, with PDO
Server OS: Linux, cgi-fcgi
Installed apps: content (2.8.13), assets (2.8.13), categories (2.8.13), perch_blog (4.6), perch_forms (1.8.3)
App runtimes: <?php $apps_list = array( 'content', 'categories', 'perch_forms', 'perch_blog', );
PERCH_LOGINPATH: /admin
PERCH_PATH: /home/intakeve/public_html/admin
PERCH_CORE: /home/intakeve/public_html/admin/core
PERCH_RESFILEPATH: /home/intakeve/public_html/admin/resources
Image manipulation: GD
PHP limits: Max upload 128M, Max POST 128M, Memory: 256M, Total max file upload: 128M
Resource folder writeable: Yes
HTTP_HOST: www.intakevets.co.uk
DOCUMENT_ROOT: /home/intakeve/public_html
REQUEST_URI: /admin/core/settings/diagnostics/
SCRIPT_NAME: /admin/core/settings/diagnostics/index.php