Raycast NOT ignoring layers

I have a problem where my raycast does not want to ignore any layers except for the ignoreraycast layer

           // Ray cast
	Ray ray = Camera.main.ScreenPointToRay (Input.mousePosition);
	RaycastHit hit;
	LayerMask layer = LayerMask.GetMask("Plane");

	// Do ray cast
	Physics.Raycast (ray , out hit, layer); // Hits "Event" Layer instead of Plane Layer

Physics.Raycast has many overloads, but i think the third parameter is the distance, not the layer mask.