Creating a Static Page

I’m trying to create a page that will still function with all the WP elements, but will include a specified PHP file.

I’ve tried using the built in Page creator (which doesn’t even display the PHP), I’ve tried adding it as an option in other files, and finally I tried just copying the index.php code into my new file.

My problem is I keep getting the error “No input file specified” on this last option. Can someone please tell me what I’m doing wrong? This is driving me nuts!