CFrame LookVector not changing???

local camcenter = workspace.CameraCenter -- this is a part that controls a camera
local cframe = camcenter.CFrame

local MaxIncrement = 10
local increment = 1

local uis = game:GetService("UserInputService")

uis.InputBegan:connect(function(input)
    print("InputDetected")
    if input.UserInputType == Enum.UserInputType.Keyboard then
        print("KeyboardInputDetected")
        if input.KeyCode == Enum.KeyCode.W or input.KeyCode == Enum.KeyCode.Up then
            print("WUPInputDetected")
            if (cframe.LookVector + Vector3.new(0, 0, increment)).Z < Vector3.new(0, 0, MaxIncrement).Z then
                print("Changing")
                cframe = CFrame.new(Vector3.new(0,0,0), cframe.LookVector + Vector3.new(0, 0, increment)) 
            end
        end
    end
end)

I am not getting any errors. The thing is that it only works once and then it freezes.

help please