How do i make this script work?

I am trying to make it to where when i press this button it locks me in first person but for some reason when i put script.Parent.Active = true it has a red squiggly line under the = sign saying Expected 'then', got '='

Script:

script.Parent.Parent.Parent.Parent.CameraMode="LockFirstPerson"

function onBananaClicked()
    if script.Parent.Disabled = true then game.StarterGui.ScreenGui.Frame.Beep.FirstPerson.Disabled = true 
    end 

script.Parent.MouseButton1Click:connect( onBananaClicked)

The 4 script.parents are caused because the button is inside a frame, inside a gui, inside the startergui, and thats inside the game.

Please help!