a href not concatinating (nodejs, ejs)

I have some trouble with some buttons that don't go to the correct route. I have an overview of items with a details button. When I click on it the route becomes

(localhost)/items/:itemname

inside this item I have another button that allows to add new data to this specific item. The link is supposed to be:

(localhost)/items/:itemname/data/newdata

but for some reason, when I click the button, it goes to

(localhost)/items/data/newdata

I tried several things, including putting the itemname in the href, until I suddenly got this route:

(localhost)/items/:itemname/:itemname/data/newdata

this is my current a href in the itemDetails.ejs file

<a href="data/newdata" type="button" class="(bootstrap stuff)">

it goes to (localhost)/items/data/newdata

could it be a problem with my gulp file? or my view engine?

via Rachelle Janssen