Second checkbox depends from another checkbox

I want make second checkbox invisible while first checkbox isnt "check". In other case i want check my first checkbox and the second should be clickable. How can i do it?

My example dosent work:

if (FirstCheckBox.Checked == true)
            {
                SecondCheckBox.Visible = true;
            }
            else if (FirstCheckBox.Checked == false)
            {
                SecondCheckBox.Visible = false;
            }