I am trying to validate four checkboxes to be true to check a master checkbox that all approvals are complete

I have a case formula looking at four individual check boxes to be checked. It seems that when two of the approvals are done, the All Complete box checks off which is not right....what am I missing here


Case(true,
[PM Approval],
[Site PM Approval],
[Refrigeration Approval],
[Equipment Approval],false)