You have quite a few issues on your page.
-
You page does not have an opening
<body>
so app connect cannot be initialized. App Connect is added to the page body. Not sure how you did manage to achieve that - probably copy/pasting things around different pages? -
Your “header” include is actually a whole HTML page, which is also wrong. It should only be the part of the page you want to include. I suggest you to follow the docs about this and include it properly, after you fix issue 1: Server Side Includes (SSI)