Hello, im quite new to SilverStripe,

I've got a Order page on the website and in the CMS i've got a page with the page type Order.
Now i want to edit the Order page, so i made OrderPage.ss to make the layout right.

<div id="page">
<div id="small_logo">
<img title="Logo IJzerleeuw" alt="Logo IJzerleeuw" src="$ThemeDir/images/ijzerleew_logo_transparant_small.png" />
</div>
<div id="page_text">
<h1>$Title</h1>
$Content
$Form
</div>
</div>

But this page isnt showing anything..
The Page.ss is showing instead of OrderPage.ss

I did dev/build?flush=1 but it isnt working.

Anyone got an idea? Thanks already!