"It is not possible to invoke an expression of type 'boolean'" in switching cameras

Here is my code:

var Building_Camera : Camera;
var Catapult_Camera : Camera;

function Update() {

if (Input.GetButton ("e")){ 
    Building_Camera.enabled(false); 
    Catapult_Camera.enabled(true);    
}

if (Input.GetButton ("r")){ 
    Building_Camera.enabled(true);
    Catapult_Camera.enabled(false);  
}

}

pretty basic, but I get the following error in all of the camera lines: It is not possible to invoke an expression of type boolean. If this code is in correct could you tell me another way to change the camera view. I mean, if I have two cameras and want to change between them. Thnks...

'enabled' is a field/property, not a function, so you want (e.g.):

Building_Camera.enabled = false;