Physics2D.Linecast ignoring walls

In my current project all enemies cast a linecast towards the player, but even when there are walls between them the raycasthit2d.transform always returns the player transform anyway, why is this happening?

RaycastHit2D ray = Physics2D.Linecast(transform.position, player.transform.position, 9);
        if (ray.transform == player.transform)
            print("in sight");

also: 9 is the layermask of the enemy so it doesn’t return itself, also just found out that when you set the layermask to wall it always returns null

So turns out the problem was my absolute misunderstanding of how layermasks work:

If you want a raycast (or in this case a linecast) to hit every layer except one you have to do this magic:

int layerMask =~ LayerMask.GetMask("Enemy");

I found this answer here: Ignore one layermask question - Questions & Answers - Unity Discussions

Thanks to @oStaiko for indirectly answering my question!