Setting up completion code generation

Question

Step 5 for setting up to display the completion code says
On the second of the two new pages (i.e., the second to last page), add the following in a php code window (i.e., dragged from the right side to the center/page)

$completion_code = value('VA02_01');
html('

BESAMPLE COMPLETION CODE: '.$completion_code.'

');

But when I add it in the php code window, it says "Warning: The function html() is not suitable or allowed in the PHP for Processing Responses."

What do I do?
I realised setting up and generating codes in SoSci survey is really inconvenient.
Kindly help