SetPrimaryPartCFrame() doesn't work when model is unanchored?

Basically as the title says. I've got a HatchMain (PrimaryPart) welded to a HatchPart, which is welded to the vehicle's chassis. The hatch opens and closes if the weld script doesn't run, but it doesn't work at all if the weld script ran. I thought it was a welding-related issue, but I'm guessing it's related to the fact it's unanchored. Anyone?

elseif not Opened.Value then -- Open
                Moving.Value = true
                for i = 1, 44 do
                    Hatch:SetPrimaryPartCFrame(Hatch.PrimaryPart.CFrame*CFrame.Angles(math.rad(CloseNumber),(0),(0)))
                    wait()
                end