Well actually VDUI should not be on qa-refapp, I suspect that something is not quite right with the way extensions configurations are intertwined on that one. You should install VDUI on a clean release of the Ref App distro (2.3, 2.4 or 2.5) and it should be ok.
You can use the SDK to do this in minutes. See ‘SDK: Help with setting up server using installed MySQL’.