OnUpdate not working. D=

[InfiniteShift]

At the moment I'm just fiddling around, trying to set up a basic clock. I'm unsure of what I'm doing wrong here.

tkClock = tkUI.CreateText("tkClock", Guiroot) --CT_LABEL
tkClock:SetAnchor(TOPRIGHT,Guiroot,TOPRIGHT,-10,-5)
tkClock:SetHandler("OnUpdate", function() 
  tkClock:SetText(GetTimeString())
end)